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GLASSMAKERS’ 


HAND-BOOK 

CONTAINING RECIPES FOR MAKING 

Flint, Bottle, Window, and Architectural Glass, Plain 
and in Colors; Plate Glass—American, French, 
Belgian, German and Bohemian Formulas; 


ALSO, 


Recipes for Strass and Artificial Gems. 


/ 


r 




o 



/ 


ED ITED/B Y 

FRANK M. GESSNER. 

i I 

ASSISTED BY 


AUGUST WEYER, 

Formerly Metal Maker, Gleason 
Manufacturing Co., Brooklyn, N.Y., 


THOS. J. IRWIN, 

Metal Maker, New Brighton Pa., 
Glass Company, 


SPECIAL CONTRIBUTORS. 


PRICE per copy, - $10.00. 


GEORGE E. WILLIAMS, 

PITTSBURGH, PA. 

1891. 


b copyright- 

MAY IS 189! 

/2~U ' ' 

^shingt«w 





8 ? 




Copyright. 

Entered according to an Act of Congress, by Frank M. Gessner, in the office 
of the Librarian ot Congress, at Washington. 

1891 . 



glassmAkers’ hand-book. 


m 


PREFACE. 


Gla iakers’ Hand-Book is not the work of a single 
indiviv nal, and though no attempt is made to sliirk respon¬ 
sibility for sncli errors and defects as this volume may con¬ 
tain, the editor does not claim, neither does he desire credit 
for whatever of merit the work may possess due to the labor 
of others, whose names may or may not be mentioned in any 
reference in the body of the work. Indeed, the hours spent 
in the laboratory and over the testing crucible, constantly 
surrounded and assisted by friends we can never forget, 
their scrutinizing care exercised in the reading of the manu¬ 
script (often hastily written), and the (sometimes, aye. often) 
too tedious proof sheets; the toning down, condensing, 
rectifying, and betimes elaborating processes to which all 
was submitted by men of toil, devoid of leisure, are among 
the most pleasant memories of “the days that are no more.’’ 
One of these friends, August Weyer, who cheerfully and 
generously gave the value of his varied technical knowledge 
and experience for the furtherance of this volume, passed 
from life while the manuscript of the work, part of which he 
revised, was still in an embryonic state. His name appears 
on the title page, therefore, as a slight recognition of services 
tendered, which would have been much augmented had 
length of life permitted. 

To Thos. J. Irwin, who has kindly corrected the proof 
sheets, constantly advised, and contributed to the volume, 
our special acknowledgment is due. 

In the preparation and compilation of this volume we 
have freely garnered from many fields, rejecting nothing 
good because it was old, and accepting nothing untested be¬ 
cause it was new. It is believed, however that we have 
cleaned from modern practice such results as will prove of 

o , 



IV 


GLASSM AKERS’ HAND-BOOK. 


value to the metal maker and manufacturer, and have re¬ 
jected all descriptive, poetical, legendary, fabulous, and 
semi-historical matter, which would have increased the size 
but added nothing to the value of the volume. 

We desire especially to acknowledge our obligation to M. 
F. Macrum, librarian of the Pittsburgh Library Association, 
and R. A. Lee, assistant librarian, for frequent “ irregular 
and unlawfulloans of books from the unkennt and 
unappreciated repository of knowledge over which they so 
intelligently and devotedly preside. 

To the founder of the Carnegie alcove of the Pittsburgh 
Library Association, that solid, though limited, nook of 
knowledge, to which we have so often gone for reference, 
confirmation and correction, and the shelved masters of 
which yielded us the glorious fruitage of their vast re¬ 
searches and labor, we gratefully express our appreciation 
and obeisance. 

We hope that to some extent a perusal of this volume 
will increase the fund of technical knowledge, and aid in 
equipping the American metal makers for that not distant 
day when we shall supply ourselves with the thousands of 
articles of bijouterie and quincaillerie now made abroad 
and annually imported in immense quantities, even in times 
like the present, when many of our own factories are idle 
because our glass industry lacks diversity, and our workmen 
are deficient in the skill and technique required in the pro¬ 
duction of those finer and minuter branches of the glass- 
makers' art, profitably pursued in the old world. 

If even to some small extent such hope is realized, and 
the encouragement extended the editor of the present vol¬ 
ume will induce abler men to give heretofore cautiously 
guarded knowledge to the trade, in ampler and better vol¬ 
umes, so that private secrets shall be transformed into pub¬ 
lic benefit, it will yield him additional pleasure and satisfac- 
H° n - Frank M. Gessner.- 


GLASSMAKERS’ HAND-BOOK. 


CRUDE MATERIALS FOR GLASS MAKING. 


Practically, all true glasses are composed of silica, or 
silicic acid, in combination with at least two alkaline or 
earthy bases, and sometimes the oxides of lead, zinc and 
other metals.. Silica, which forms the main ingredient, is 
very abundant in nature, forming a principal constituent in 
rocks and stones, and existing in a free and almost pure 
state in flint, agate, chalcedony, rock crystal and quartz, the 
last two being its lowest form. Formerly, flint—silex—cal¬ 
cined and ground, was used as the source of the silica, and 
hence was derived the name : Flint Glass. 

Sand, containing over 99 per cent, of pure silica, is abund¬ 
ant in the United States. It exists in almost inexhaustible 
quantities in Juniata county, Pennsylvania; Hancock 
county, West Virginia; Fox River, Illinois; Berkshire 
county, Massachusetts; Crystal City, Missouri; Minneapo¬ 
lis and St. Paul, Minnesota; besides the States of Ohio, In- 




GLASSM AKERS* HANDBOOK. 


O 

(liana, New Jersey, New York, Maryland, Georgia and 
Alabama have vast quantities of the purest glass sand. 

Soda-ash, potash (potassa) and salt cake (Glauber salt, 
sulphate of soda) are now manufactured and commercially 
obtainable in such pure form that but little description is 
necessary. Potash is more efficacious than soda in 
effecting fusion in the melting process. A more brilliant 
lustre results from the use of soda, but a blueish-green tint 
is thereby imparted to the glass. No coloring action is ex¬ 
erted by potash, but the brilliancy of the glass is somewhat 
diminished by it. Glauber salt is used in the manufacture 
of bottles and common window glass, being preferable on 
account of its cheapness. It is not used without the accom¬ 
paniment of a small quantity of soda, generally, in Ameri¬ 
can factories, about 3 to 6 pounds of soda, 35 to 40 pounds 
of Glauber salt to 100 pounds of sand, constituting the 
usual proportions of batch in window glass factories. The 
use of charcoal, usually 2 pounds to 100 of sand, is resorted 
to when using Glauber salt, so as to facilitate fusion and ob¬ 
viate the presence of glass gall (salt water). 

In the manufacture of plate glass the use of Glauber salt 
has been tried with indifferent success, and, mostly on ac¬ 
count of the greater power in effecting fusion, carbonate of 
soda is still largely adhered to in this branch of glass manu¬ 
facture. 

Lime forms an important constituent in most kinds of 
glass, and may be introduced either as a carbonate, or slacked 
or burned. Finely ground unburned lime of very pure 
quality is now commercially obtainable, and is preferred on 
account of the greater agitation resulting in the batch from 
the use of lime in its raw state. Limestone, however, which 
contains proto-carbonate of iron must be avoided if color is 
an object, for the presence of iron always imparts a yellow or 
green tint to glass. For this reason foreign glassmakers 
often use chalk (which is a carbonate of lime) in making fine 


GLASSMAKERS’ HAND-BOOK. 


3 


colorless glass. This chalk is free from iron, and is obtained 
from mountainous deposits which exist in Europe. The ac¬ 
tion of lime is to render the alkaline silicates insoluble, and, 
when rightly balanced by the other ingredients, it promotes 
the fusion of the batch and improves the quality of the 
glass; but, if used in excess, the glass becomes hard and 
difficult to work, and subject to devitrification. Besides, an 
excess of lime must be avoided, because in too large quanti¬ 
ties it retards fusion and violently attacks the pots, thus en¬ 
dangering the color and purity of the metal. 

Baryta, or heavy spar, has been used in European factories 
to impart greater density and higher polish to finer grades of 
glass. Carbonate of baryta has been substituted for carbon¬ 
ate of soda in the manufacture of English plate glass, and is 
said to produce a glass that is very little affected by atmos¬ 
pheric changes, and therefore its use lias been found admir¬ 
ably adapted to the manufacture of lenses for optical instru¬ 
ments. Baryta, however, has not found its way into general 
use in glass manufacture. It may become an important fac¬ 
tor in time, as it is being extensively manufactured, and is 
obtainable in great purity, is free from iron, and has been 
successfully used as a substitute for oxide of lead • in the 
manufacture of crystal glass. 

Alumina, though rarely purposely introduced into the 
batch, is always accidentally present, partly as an accompa¬ 
niment of other ingredients, or brought there from the sides 
of the pots through the action of the alkalies. It lias been 
purposely used in making white opaque and opal (from 8 to 
10 per cent.) mainly, however, in the form of cryolite. To 
decrease the attack on the pots resulting from t he use of cry¬ 
olite the aluminate of soda, prepared from cryolite, has been 
used with satisfactory results in the manufacture of white 
opaque and opalescent glass. Experience proves that one 
part of such aluminate ot soda equals one-seventh part ot 
cryolite and 0.1 part of soda in otherwise properly propor- 


glassmakers’ hand-book. 


• 4 

tioned batches, and effects a saving in pots not otherwise at¬ 
tainable with cryol ite glass. 

Iron is nearly always present, as traces of it are almost in¬ 
separable from the sand, sulphate of soda (when employed), 
lime and chalk, and the yellow or greenish tint resulting 
from its presence, where color is an object, must be neutral¬ 
ized by decolorizing materials. 

Cullet is added in varying proportions, from 80 to 100 lbs. 
to 100 lbs. of sand, generally, and being more fusible than 
the raw materials, facilitates fusion. It should always be 
carefully cleaned, sorted, and properly pulverized. In the 
manufacture ot the finer grades of glass, however, or where 
homogenity and uniformity of product is desirable, the quan¬ 
tity and quality of cullet used should be carefully guarded, 
as glass, by repeated remelting, loses life, fluidity, strength 
and resistance, and deteriorates generally because of volatili¬ 
zation. 

In bottle and window glass manufacture, except in the 
finer grades, the amount of cullet may not be material, but 
even for high pressure bottles the amount used should be 
cautiously guarded, as experience demonstrates that large 
amounts of cullet, indifferently added, seriously affect not 
only the strength of the ware, but, what is of far greater im¬ 
portance, greatly decreases their resistance to the influence 
of acids, which form a part of the liquors, wines or aerated 
waters they are intended to contain. 

OTHEE RAW MATERIALS. 


In the United States, where there has heretofore been no 
scarcity of pure sand along all the lines of development of 
the glass industry, necessity, nor the desire for cheaper sub¬ 
stitutes, has seldom led manufacturers to employ equivalents 
for sand. The time may come, however, when the glass in¬ 
dustry of this country will depart from the old lines and 



GLASSMAKERS’ HAND-BOOK. 


5 


seek a home in the far West and South (points heretofore 
almost untouched.) At present, and for many years past. 
California, which must eventually become an extensive wine 
exporting, as it is now a vast wine producing State, has con¬ 
tained only one small glass factory, and while drawing its 
supply of bottles, partially through patriotic preference and 
quicker response to orders, from Xew Jersey and some 
Western manufacturers, yet finds it profitable to import the 
bulk of its wine bottles from European factories. 

The South is certain to develop into a far greater fruit 
producing and exporting country than has heretofore gener¬ 
ally been anticipated, and will need glass jars, cases, cans 
and bottles in undreamed of variety and vast quantities. 

The freight cost to both California, or, more properly 
speaking, the far West and the virgin South, from the old 
and present largest glass producing States of Pennsylvania, 
Ohio, Hew Jersey, Indiana, Illinois and Missouri, would be 
sufficient to pay handsomely on all necessary investment for 
local glass manufacturing. 

The time may come, therefore, when in new localities those 
substitutes for sand, which have been successfully used in 
some localities in the old world, will be sought for, and ap¬ 
plied. 

The West and South is especially rich in such substitutes 
for sand, as experience has proved reliable and profitable. 
Hence we append tabulated analysis of some of these mate¬ 
rials : 


BASALT. 


Silica . 

HafFenberg, Bohemia, 
Klaproth. 

44.5 

Staffa, Scotland 
Kennedy. 

48. 

Alumina. 

O-s-irip of’ iron . 

. 16.75 

20.— 

16. 

16. 

fJ'Y'irlp . 

0.12 

0. 

IjilTIC . 

9.5 

9. 

Magnesia. 

Soria . 

2.25 

2.6 

0 

4 

Moisture and volatile matter. 

2.— 

6 


99.72 99. 











6 


GLASSM AKERS 5 HAND-BOOK. 


Other basalts, notably that of Meissen, analyzed by Krue¬ 
ger, contained 55 per cent, of silica. 


OBSIDIAN. 

Klaproth. 

Silica. 88.n0 

Alumina. 5.87 

Potash. .. 

Soda. . 

Lime. 2.00 

Bitterearth. . 

Oxide of iron. 1.75 

Oxide manganese.•.. - 

Moisture. . 


Erdmann. 

82.70 

9-40 


2,45 

1.21 

1.21 

2.62 

1.80 


Lipari. 

74.05 

12.97 

5.11 

4.15 

0.12 

0.28 

2.73 


0.22 


98.12 100.88 99.63 

Lava and pumice stone, used in some parts of the old world 
with indifferent success on account of their varying composi¬ 
tion, have been shown to contain fair proportions of silica. 
Thus lava analyzed by Bergman contained 46.26 per cent.; 
Ilgner's analysis showed 48.94, while still other chemists 
(Myer and Donnenberg) found lava containing 57 per cent, 
of silica. Pumice stone has been found to contain from 50 to 
58 per cent, of silica, and their proportions of alumina and 
iron, indicate their usefulness in the manufacture of bottles 
and colored glass. 

Besides the materials enumerated, granite seems to have 
been more constantly used than all others, and with more 
satisfactory results, especially at the works of Frederick Sie¬ 
mens, Dresden. In some cases 14 per cent, of alkali has been 
found in granite, while with 18 per cent, of alumina and 
traces only of iron, lime and magnesia, a very clear glass 
should be obtainable. The analysis of St. Gotthard granite 
showed— 


Silica. 


65.75 

Alumina. 

Oxicle of iron. 

.) 

18.28 

Lime. 

Magnesia. 

:::::::::::: f 

Trace. 

Soda. 

14.17 

Potash. 


1.44 


99.64 


The addition of about 10 per cent, of lime would make a 
fair working glass. 


In all these materials, however, 


as well as in blast furnace 






























GLASSMAKERS’ HAND-BOOK. 


slag, the varying proportions offer the greatest objection, and 
a glass of uniform quantity has heretofore not been obtaina¬ 
ble. With constant vigilance, and repeated chemical analv- 
sis of the batch constituents and of the glass obtained, so as 
to change the batch to suit the varying propertions of the 
basic materials, would no doubt give good results, but pre¬ 
supposes a greater cost and scarcity of pure sand than has 
heretofore been experienced, and would compel the employ¬ 
ment of more technical knowledge than has been customary. 


DECOLORIZING MATERIALS. 


All glass exhibits a tendency to change color or fade. To 
obviate or decrease this natural defect certain materials are 
employed with the special object of counteracting it. To this 
class belong binoxide of manganese, arsenic and nitrate of 
potassa. The accidental elements which usually discolor 
glass are iron and carbon, or carbonaceous matter, and the 
presence of these are always objectionable, except in the 
coarser kinds of ordinary bottle glass, or rough architectural 
glass. In all such undesirable discolorization the above- 
mentioned substances are employed to neutralize or counter¬ 
act discoloration by means of forced oxidation. 

The binoxide of manganese, added to the batch in' small 
quantities, neutralizes the greenish tint imparted by protox¬ 
ide of iron by covering or masking such greenish tint with its 
complementary color of red, and by their combination trans¬ 
mitting white light; not, as formerly supposed, in bringing 
the silicate of protoxide of iron to the state of a silicate of the 
sesquioxide. The use of manganese has, however, been 
largely abandoned in European factories during latter years, 
especially in the manufacture of window glass and fine flint 
ware, because, as the researches of Gaffield have shown, the 
fading of glass, exposed to the action of air and sunlight, has 
been demonstrated to lie directly traceable to the use of man- 



8 


GLASSM AKERS’ HAND-BOOK. 


ganese. Used in excess, it imparts an amethyst tint to the 
glass. Small quantities of oxide of nickel and antimony, ac¬ 
cording to Kohn, act as efficacious decolorizers in place of* 
manganese, without the deleterious effects above noted. 
Arsenic, in small quantities, promotes decomposition of the 
other ingredients, and tends to dissipate carbonaceous impu¬ 
rities not otherwise disposed of. Used in excess, however, it 
produces an objectionable milkiness in the glass, which age 
usually increases. 

Other decolorizing materials sometimes resorted to are 
smalt, either of cobalt or zaffre, used in small quantities of a 
few ounces, which, like manganese, mask the poor color im¬ 
parted by other materials. ^Generally speaking, however, the 
decolorizing agents are those which act by oxidizing the car¬ 
bon or the protoxide of iron, and thereby actually expelling 
the lime. In this way nitrate of potassa reacts before the 
glass enters into perfect fusion ; arsenious acid, arsenic acid 
and their salts exert their influence at a temperature above 
the fusing point and are volitilized. 


SPECIAL ACTION OF DIFFERENT CONSTITUENTS. 


Although, in a purely chemical view, the potash, soda, 
lime, oxide of lead, etc., perform the same part, it is, never¬ 
theless, very evident that, in practice, the employment 
of one of these bodies cannot be substituted indifferently for 
that of one or other of its analogues. Their necessity results 
in the product differences of fusibility, of ductility, of hard¬ 
ness, etc., which must always be taken into consideration; 
carefully guarded, and wisely provided against. Hence the 
necessity of closely watching and recording results and 
changing ingredients of the batch so as to produce, as nearly 
as possible , such quality of glass as is most desirable. 

The varying quality of sand, soda, lime, potash, etc., the 
careless addition of cullet by indifferent workmen, the insuffi- 



9 


GLASSMAKERS 7 HAND-BOOK. 


cient mixing of the batch, etc., all contribute towards making 
glass far different than that which one would have a right to 
expect if proper care was continually exercised at every 
point, and hence the strictest oversight and never-sleeping 
vigilance must always be exercised in all matters of detail, 
however small, if a uniform grade and high class of goods are 
to be produced. For these reasons it is well to bear in mind 
that the silicates of soda and potash are the most fusible, and 
so much the more in proportion to the greater amount of the 
alkaline bases. Potash is more powerful than soda in effect¬ 
ing fusion. The silicates of lime are much less fusible than 
those of the alkalies, and the silicates of magnesia are. not 
more fusible. Lime increases the hardness of the glass, and 
adds more to its lustre than the alkalies, without coloring 
the product. 

The silicates of alumina are still more refractory; indeed, 
of all the ingredients, alumina exerts the most powerful effect 
in increasing the difficulty of fusion. 

The silicates of the protoxides of iron and manganese are 
more fusible than those of lime and magnesia, especially 
when present in nearly equal proportions; acting on each 
other as above described under declorizing materials. 

The silicates of the oxides of lead are the more fusible in 
proportion to the greater amount of the base. With equal 
equivalents the silicate of lead melts at a red heat. In fact, 
oxide of lead exerts a directly opposite action to that of 
alumina, being a prominent ingredient in the easy fusible va¬ 
rieties of glass, which are also characterized by great soft¬ 
ness, a high brilliancy, perfect absence of color, and by the 
property of refracting light more powerfully than any other 
kind. The silicates of the oxide of zinc present similar 
properties, but zinc has not generally been adopted as a sub¬ 
stitute for lead, as glass containing the former must be 
worked out of the pots rapidly after firing, or it is liable to 


10 


GLASSMAKERS* HAND-BOOK. 


acquire a yellow tint. Such yellow tint can, however, be 
masked by the addition of oxide of nickel. 

Binoxide of manganese, besides being a decolorizer, as 
already noted, is used in the manufacture of black, violet and 
brown glass, and, in combination with copper and iron oxides, 
produces the so-called “ London smoke ” color in cathedral 
and architectural sheet glass. 

Oxide of cobalt produces a deep blue, which is not ap¬ 
proached in richness by any other material. Zaffre, a cruder 
form of the oxide of cobalt, has been used for a cheap blue, 
but it lacks the depth and richness of the cobalt glass. 

Oxide of Uranium produces the best yellow. Charcoal, 
finely pulverized, produces an inferior yellow, and, in in¬ 
creased quantities, a dark, lustreless brown or amber. A su¬ 
perior yellow is obtained by roasting sulphide of antimony to 
the state of antimonious acid, and melting it with from 3 to 
5 per cent, of undecomposed sulphide of antimony. An orange 
yellow is prepared with glass of antimony, minium, and a 
little oxide of iron. Oxide of silver colors glass from a light 
yellow to an orange. 

Green is produced either by protoxide of iron, protoxide 
of copper or oxide of chromium. The tint produced by the 
first of these lias little brilliancy. The oxide of copper yields 
a beautiful emerald. For this purpose the glass is mixed 
with the product obtained by heating copper to redness with 
access of air, or with -powdered verdigris, which is then de¬ 
composed in the fire and converted into oxide by oxidizing 
agents. Care must he taken to prevent the protoxide of iron 
from being converted into sesquioxide, and the oxide of cop¬ 
per from being reduced to suboxide. The oxide of chro¬ 
mium, obtainable as a pigment in commerce, yields the pur¬ 
est and most brilliant grass-green hue, but it is too costly for 
common use. Ruby, gold, or copper ruby, are among the 
rarest and most difficult colors to obtain with any degree of 
uniformity. Gold and copper both yield an intense ruby. 


11 


GLASSM AKERS 5 HAND-BOOK. 

Copper, as a rule, colors deeper, on account of its greater fu¬ 
sibility. Gold ruby is used both as a body and easing glass, 
but invariably with lead flint batch ; copper, because of its 
deep color, is only used for casing. For further instruction 
relative to the preparation of gold see ruby recipes. 

Gold or copper, as a rule, must be intimately incorpora¬ 
ted with the batch, and the most scrupulous cleanliness and 
greatest purity of all ingredients must be observed through¬ 
out. Batches made of chloride of potash and sulphate of 
soda are useless for ruby, for the gold will not distribute itself 
as long as such batches contain glass gall. The melt must 
be well graduated and the furnace temperature be carried to 
a sufficient intensity for proper results, as a low temperature 
will produce a glass lacking uniformity of character, and im¬ 
part an objectionable brown tint. The color often develops 
at a red heat; at other times, however, only at the point of 
fusion. The color is developed more rapidly in proportion 
as a greater amount of gold is used. After the glass has 
cleared, experience has shown that a forced and rapid reduc¬ 
tion of the furnace temperature is favorable to the develop¬ 
ment of the ruby color. 


GENERAL HINTS ON COLORING. 


Yellow is produced by either charcoal, antimony, silver, 
or oxide of uranium. A fine yellow is produced by roasting 
sulphide of antimony to the state ol antimonious acid and 
melting it with from ,3 to 5 per cent, ol undecomposed sul¬ 
phide of antimony. An orange yellow is obtained with an¬ 
timony, minium and a little oxide of iron. Silver can also 
be used in the muffle, powdered clay (the vehicle) and cho- 
ride of silver applied with a brush to glass articles in the 
form of a paste. To get a proper effect glass thus stained 
should contain alumina. Oxide of uranium (though too costly 



12 


GLASSMAKERS* HAND-BOOK. 

for common use) applied in the same manner will impart a 
delicate yellow of a green isli hue. 

Red, of different shades, is obtained by using oxide of 
iron, sub-oxide of copper or gold, of different preparations. 
The oxide of iron may either be used in the shape of pure 
oxide, prepared by heating the nitrate, or in the state of 
blood-stone or ochre. The manner of preparing the gold is 
given with the ruby recipe. The German method, as fol¬ 
lowed by Fuchs, was to obtain purple of Cassius by mixing a 
solution of sesquichoride of iron with acqueous protocho- 
ride of tin till the yellow color is converted into pale green, 
then precipitating the gold solution with the mixture thus 
formed. The protochoride of iron does not affect the pro¬ 
duct. In a moist state the substance thus obtained is purple 
red, and, when dry, brown. 

According to Fuss, a ruby glass is obtained by mixing with 
the batch a small quantity of oxide of tin and the gold solu¬ 
tion. Experience has shown, however, that the addition of 
the oxide of tin is not necessary. The amount of gold used, 
it need scarce be hinted, regulates the intensity of the color, 
and as this glass is generally used only for flashing or casing, 
the color must be regulated according to the color of the arti¬ 
cles to which it is to serve as a casing. 

Blue is obtained by the use of the oxide of cobalt, and is 
applicable to lead or leadless glass. Zaffre, a lower grade of 
cobalt, has also been used with success for a cheap blue glass. 
A cheap blue may also be made by the use of copper scales, 
four ounces to 100 of flint batch giving a light sky blue. 

Green is produced either by protoxide of iron, protoxide 
of copper or oxide of chromium. The tint produced by the 
protoxide of iron, however, lacks brilliancy. The oxide of 
copper yields a beautiful emerald. The oxide of chromium 
makes the purest and most brilliant grass green, but is too 
costly for general use or common glass. 

W hite Opal is produced with calcined bones, cryolite or 


13 


glassmAkers’ hand-book. 

oxide of tin. Cryolite is objectionable, from the fact that it 
attacks the pots. German glassmakers have used Baker 
guano for opal. It is necessary to calcine it before using, in 
order to free it from organic substances. It has the advan¬ 
tage of containing no iron, and distributes itself evenly in the 
batch. Opacity is obtained by increasing the quantity of 
bone ashes (phosphate of lime) or the oxide of tin. 

Black is produced by an excessive use of manganese and 
the oxides of iron or cobalt. Manganese, on account of its 
cheapness, is preferable. 

Gray is produced by neutralizing the violet color imparted 
by manganese with the oxides of iron or copper., The so- 
called “ London smoke ” is thus obtained, and is much used 
in the manufacture of architectural glass. The manganese 
and iron may be dispensed with, and the same effect be ob¬ 
tained by the use of oxide of nickel. 

Violet is generally made with manganese, and the various 
shades, from the lightest to the deepest black, may be ob¬ 
tained by varying the quantity of manganese used. 

Oxide of iron colors glass either green or yellow, according 
to the nature of the oxide, the silicate of the protoxide of iron 
being green, and that of the protoxide yellow, of a slightly 
brownish tint. 

Copper forms two oxides, the suboxide and the protoxide; 
the suboxide colors glass red, while the protoxide renders it 
green. 

Black oxide of manganese colors glass violet, rose and pur¬ 
ple, according to the quantity used ; il added in excess it col¬ 
ors densely black. 

Sesquioxide of chromium imparts a beautiful green color 
to glass. 

Oxide of uranium produces an opalescent effect of yellow, 
with a green tinge. 

Oxide of silver stains glass from a delicate lemon to a deep 
orange, in proportion to the quantity used. Oxide of silver 



14 


/ 


GLASSM AKERS’ HAND-BOOK. 


is not mixed with the batch, however, because it does not 
readily unite with oxygen, and, when it has done so, it loses 
its oxygen again at a high temperature, and becomes reduced 
to the metallic state ; and, inasmuch as metals have no effect 
whatever in staining silicates, glass made in this way would 
not have the yellow color which silver, applied to its surface 
and heated at a much lower temperature in the muffle, im¬ 
parts to it. The temperature to which the batch must be 
heated to effect fusion is so high that the oxide of silver, 
formed at a lower temperature, would be reduced to the 
reguline or metallic state. 

COMPOSITION OF GLASS. 


Glass, as before indicated, consists generally of a mixture 
of two or more silicates that have been united by fusion into 
a homogeneous, hard and brittle mass. The silicates which 
constitute ordinary glass are chiefly those of potassium, so¬ 
dium, calcium and lead; iron, zink, manganese, barium and 
aluminum silicates are also frequently present in small pro¬ 
portions, and some kinds of glass also contain borates. 

The following table gives the composition of different 
kinds of glass: 





Potash. 

Sand. 

Soda. 

Oxide lead. 

Lime. 

Manganese. 

Analyst. 

Oxide iron. 

Alumina. 

Window glass, 

English. 

69-00 — 

11-10 12-50 — 

_ 

7-40 .— — 

ii 

ii 

French. 

70-00 — 

15-00 13-40 — 

— 

1-50 0-10 — 

Plate 

ii 


75-90 — 

17-50 

3-80 — 

— 

2-80 — Payen 

a 

i i 

Aix-la-Chapelle 

78-75 — 

13-00 

6"50 — 

— 

1-75 — Benrath 

Bottle 

ii 

Bohemian. 

58*40 1"80 

9-90 18-60 — 

— 

2-10 8-90 Maumene 

Bohemian 

i i 


71-70 12-70 

2-50 10-30 — 

0-20 8-40 0-30 Berthier 

ii 

ii 


76-00 15-00 

— 

8-00 — 

— 

P00 — Peligot 

Plate 

ii 


67-70 2M0 

— 

9.90 — 

— 

1-40 — 

Bottle 

ii 

Sevres. 

53*55 5*48 

— 

20-22 — 

— 

6 01 5-74 Dumas 

ii 

ii 

St. Etienne. 

60-00 3-10 

— 

23-30 — 

1-20 0-00 4-00 Berthier 

Optical 

ii 

German. 

62-80 22-10 

— 

12-50 — 

— 

2-60 — Dumas 

Crystal 

ii 

French. 

58-00 8-90 

— 

2-60 32-50 

— 

— — Payen 

ii 

ii 

English. 

59-20 9-00 

*- 

— 28-20 

— 

— 0-40 Berthier 

ii 

ii 

ii 

51-90 13-70 

— 

— 33-30 

— 

— — Faradav 

Optical 

ii 

Gninand’s. 

42-50 11-70 

— 

0-50 43-50 1-00 1-80 — Dumas 



































GLASSMAKERS* HAND-BOOK. 


15 


Characters.— Glass as ordinarily met with is a homoge¬ 
neous mass possessing the peculiar texture characteristic of 
alkaline silicates after they have been melted ; it has also a 
peculiar lustre, and is usually transparent as well as color¬ 
less, unless it contains a large amount of metallic oxides 
which communicate to it color and opacity. At ordinary 
temperatures it is hard and brittle; the fracture is conclioi- 
dal; in thin sheets or threads glass has some degree of flexi¬ 
bility ; when heated to a sufficiently high temperature it be¬ 
comes plastic and ductile. The characters of glass vary ac¬ 
cording to the particular nature as well as the relative pro¬ 
portions of the silicates it contains. The greater the amount 
of silicate in glass the less fusible it is ; the greater the 
amount of alkali the more fusible it is. The presence of a 
considerable amount of lime silicate renders glass less 
readily fusible. 

The specific gravity of different kinds of glass differs 
slightly, as shown in the following table by Dumas: 


Bohemian glass. 2 39(1 

Crown glass. 2'487 

Mirror glass. 2 - 488 to 2'506 

Window glass. 2 (542 

Bottle glass. 2 732 

Crystal or flint glass. 2 900 to 3'255 

Optical flint glass. 37300 to 3 (500 

ACCORDING TO FARADAY : 

Crown glass. 2 .5448 

Plate glass. 2 5257 

Flint glass.3 2900 

Guinand’s flint (optical). 3 (51(50 

Faraday’s glass (Boacic acid). 5-4400 

ACCORDING TO MUSPRATT .' 

Plate glass (Ravenshead). 2 439 

Crown glass. 2%520 

Green hollow ware (St. Helens). 2(584 

Common green bottle glass. 2 715 

White flint (English). 3 000 

English crystal (Leith). 3T89 


When hot glass is rapidly cooled it becomes very brittle; 
this is especially the case when the pieces are thick, as the 
cooling then takes place very unequally, the outer parts cool¬ 
ing much more quickly than the interior. Glass in this con- 




















16 


GLASSMAK ERS’ HAND-BOOK. 


dition is readily affected by change of weather, slight vibra¬ 
tions, etc., and is more apt to crack the more rapidly it has 
been cooled. When a drop of red-hot glass is allowed to 
fall into cold water the surface cools very quickly and be¬ 
comes hard, while the inner portion is still very hot, and 
consequently expanded. When the interior also cools it 
cannot contract, owing to the solidity of the outer surface. 
Glass drops thus prepared are known as Rupert’s drops, or 
devil’s tears ; they terminate in a line thread, upon breaking 
which the entire drop explodes, and is converted into a fine 
powder. When the experiment is conducted in a glass ves¬ 
sel filled with water, and having a narrow mouth, the force 
of the explosion of the glass drop is sufficient to break the 
glass vessel. The pulverization is due to the unnatural and 
constrained arrangement of the glass particles, consequent 
upon the rapid cooling, and only a slight vibration is suffi¬ 
cient to effect their mutual repulsion. The so-called Bolog¬ 
nese flasks have a similar construction. These are small 
flasks with verv thick sides that have been verv ranidlv 
cooled in the air ; a grain of sand allowed to fall into one of 
these flasks is sufficient to cause it to crack with a slight 

c“> 

report. 

In order to render glass proof against rapid change of tem¬ 
perature, such as takes place when hot water is poured into 
a glass vessel, as well as the external influences, it must un¬ 
dergo a process of very slow cooling, which is called anneal¬ 


ing. 

A remarkable change in glass, through which it becomes 
dull, opaque and porcelain-like, is termed devitrification. It 
takes place when glass is kept for a long time at a tempera¬ 
ture near to its melting point, or when it is very slowlv 
cooled; also on heating glass in the flame of a blowpipe, 
which is not sufficiently hot to melt the glass. This devitri¬ 
fication is probably due to the more fusible alkaline silicates 
limiting at a temperature insufficient to fuse the more refrac- 


GLASSMAK ERs’ HAND-BOOK. 


17 


tory silicates, which are consequently separated in a crystal¬ 
line condition. The old theory that devitrification is due to 
the volatilization of alkali has been refuted by the results of 
a number of researches. 

A very curious phenomenon is that of the coloration by 
sunlight of certain kinds of glass; they acquire first a yel¬ 
lowish color, which gradually changes to violet. This color¬ 
ation is probably due to the presence in the glass of iron 
and manganous oxides, the first reaction consisting in the 
higher oxidation of the ferrous oxide, producing a yellow 
color in the glass ; the protracted action of light and air then 
oxidises the manganous oxide, the delicate violet color of 
which blends with the yellow of the iron oxide, coloring the 
glass red; when still more manganese is present the glass 
assumes a violet color. 

Hydrofluoric acid attacks all kinds of glass, decomposing 
the silicates of which it consists, and forming silicon fluoride, 
water, and fluorides of the metals contained in the glass. 
The property of hydrofluoric acid is taken advantage of in¬ 
dustrially for glass engraving. 

The resistance of glass to atmospheric and other influences 
decreases as the amount of alkali increases; glass containing 
a large amount of alkali readily loses its lustre and becomes 
cloudy, and it is more easily acted upon both by hot and 
cold water than glass which is rich in silica. 

Atmospheric moisture is especially injurious to glass, the 
effect being in proportion to the greater amount of bases in 
the glass. This is often seen in window panes made of bad 
glass, which after a short time become dull, the effect being- 
due to the separation of a very thin film of silica upon the 
surface of the glass, by the simultaneous action of atmos¬ 
pheric moisture and carbonic acid upon the silicate of which 
the glass consists, and it occurs with greater rapidity in pro¬ 
portion to the degree of moisture and heat to which the win¬ 
dow is exposed 5 hence the windows of stables and hot-liouses 


18 


GLASSMAKERS’ HAND-BOOK. 


very quickly become dull. The action of water upon glass 
is manifested in an especially unpleasant manner in optical 
glasses containing a large amount of alkali. When glass of 
this kind, owing to its slightly hygroscopic nature, becomes 
coated with moisture, the water gradually decomposes the 
glass, rendering it dull, and, in course of time, useless. 

The behavior of glass towards boiling water, different acids 
and saline solutions lias been investigated by Emmerling. 
He found that the action of boiling solutions and boiling 
water upon glass is, within certain limits, proportional to the 
length of time exposed. With new vessels it is somewhat 
greater at first (during the first hour) and diminishes with 
longer use. The action is also proportional to the amount 
of glass surface exposed to the boiling liquid. 

The action of boiling liquids upon glass during a given 
time is independent of the amount of liquid evaporated. The 
action decreases with the decrease of temperature of the 
liquid. Glass is attacked by even small quantities of alkalies. 

The action of most acids, especially in a dilute state, upon 
glass, is even less than that of water, but sulphuric acid is an 
exception to this rule, as it attacks glass more powerfully 
than water. Glass is acted upon more powerfully than by 
water, by solutions of salts whose acids form insoluble cal¬ 
cium salts, such as sulphates, phosphates, carbonates and oxa¬ 
lates, the action increasing with the concentration of the so¬ 
lutions. On the other hand, solutions of salts whose acids 
form soluble calcium salts, such as chlorides, or nitrates, etc., 
attack glass less strongly than water, the action decreasing 
with the concentration of the solutions. 

Varieties of glass differing only slightly in their percentage 
composition have nearly an equal power of resistance. The 
Bohemian (potash) glass resists reagents, especially acids, 
better than soda glass. The constituents of glass dissolve 
in about the same ratio as they are contained in the glass. 

Benrath recommends as a base for first-class Bohemian 


GLASSMAKERS 5 HAND-BOOK. 


19 


crystal glass a composition approximating: Sand, 100; re¬ 
fined potash, 30 ; slacked lime, 16 ; total, 146 ; and deduces, 
on the presumption that the potash is 70 per cent., and the 
lime 90 per cent., pure, that the composition would be: Sand 
77 - 0, soda 144), and lime 9*0. 

An excess of lime renders glass refractory and more liable 
to divitrification. The best approved practice in the manu¬ 
facture of soda-lime glass shows that the composition of the 
batch must closely approach: 1 of lime, 1 of soda, and 

sand, 6 ; or, soda, 5 ; lime, 7 ; and sand, 36 ; and as a medium 
and variable base for a good soda-lime glass: 


Sand. 75'4 per cent. 

Soda. 118 “ 

Lime. 128 “ 

100-0 

From careful analysis the following formulas for clear soda 
and lead glasses are given : 


SODA GLASS. 


Sand 

Soda. 

Lime 


711 per cent. 

170 

11-9 


LEAD GLASS. 


Sand. 

Soda. 

Red lead 


52 4 per cent. 

12-5 

351 

100-0 


The following analysis of widely different glasses shows 
how closely allied all the formulas practiced by people far 
apart are in reality, as well as the fact that considerable lati¬ 
tude and elasticity are allowable, without running into dan¬ 
gerous extremes; and yet it will be noticed that with the 
exception of strass, heavy lead flint and optical glass, the 
amount of the silica base is nearly the same in all formulas : 













20 


GLASSMAKERS’ HAND-BOOK 


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It will be seen from the foregoing analysis that insofar as 
the proportion of lead is increased (to 40 per cent, and over) 
in crystal for optical purposes, where large refracting power 












































GLASSM AKERS’ HAND-BOOK. 


21 


is desirable, one is compelled to sacrifice other advantages, 
such as resistance to acids and hardness of surface. 

In common bottle glass we find as high as 10 per cent, of 
oxide of iron, and while the discoloring effect is of no conse¬ 
quence in this particular branch of manufacture, or is only 
of secondary consideration, the utmost care is exercised in 
the manufacture of plate and fine flint glass, where the least 
abberation of color from any source is very objectionable. 

The composition of all glass to be blown or pressed into 
permanent forms, and especially those that are afterwards to 
be fashioned, ennobled or refined by additional artistic and 
costly labor, should be most carefully guarded at all points, 


because minute and extensive researches have shown the 
deleterious influence of sunlight on all indifferently com¬ 
posed glasses. Thus it has been shown by Mr. Thomas 
Gaffield, of Boston, after a series of experiments upon differ¬ 
ent kinds and qualities of glass from France, England, Ger¬ 
many, Belgium and America, that glass exposed to sunlight 
undergoes various changes in color. Thus, the changes in 
colorless glass after exposure are from white to yellow, from 
green to yellow-green, from brown-yellow to purple, from 
green-white to blue-white, and from blue-white to darker 
blue, according to the length of time of exposure to light. 
Although colorless glass can be exposed to a furnace heat 
without changing color, when the same glass has been ex¬ 
posed to sunlight and has acquired the peculiar orange and 
purple lines, if reheated the original color will reappear. 
This change, therefore, cannot be attributed to heat. In pot 
metals of intermediate colors, such as brownish, yellowish, 
and rose or purple, the change was found to be quite rapid, a 
few days in some instances being sufficient to show a per¬ 
ceptible change. Mr. Gaffield draws the conclusions from 
his experiments that the peculiar shades of colors found in 
some old cathedral glass are not owing to peculiar mixtures 
which some writers on glass claim are a u lost art,” but must 


oo 

— 


GLASSM AKERS* HAND-BOOK. 


be the result of long exposure to the rays of the sun. This 
change of color has been attributed to a great extent to the 
use of manganese, singularly known as a decolorizer among 
glass-men. Many of the European manufacturers are be¬ 
lievers in this theory, and have discontinued its use on that 
account, or have decreased the proportion used. M. Bon- 
temps mentions that glass containing manganese has been 
found unfit for liglit-house lenses. Glass containing lead, 
however, even in a proportion as small as five per cent., he 
asserts remains perfectly colorless while exposed to the sun. 
Peligot believes that to the use of manganese these changes 
of color may, to a great extent, be attributed; the green tint 
of ordinary glass being attenuated by the action of sunlight, 
the peculiar purple color due to manganese becomes pre¬ 
dominant. 

PREPARATION OF THE BATCH. 


The greatest care should be exercised in the mixing room, 
and every single manipulation should be conscientiously at¬ 
tended to, not only in the manufacture of flint, but in win¬ 
dow and even the coarser grades of bottle glass. 

It is a matter of no consequence that many successful 
practical metal makers disdainfully regard all theoretical, 
technical and scientific disquisitions on glass manufacture, 
and it is not here a matter of dispute that, with the same 
uniform ingredients, men of no technical knowledge what¬ 
ever have fairly succeeded, while many so-called technical 
and “ book-learned tender-feet ” have woefully failed in prac¬ 
tice. 

And yet it is thought that no one will deny that a general 
and thorough technical knowledge, combined with well-bal¬ 
anced judgment, common sense, varied observation and ex¬ 
perience, will lead to vastly better results than any mere 
blind adherence to old formulas. Every glassmaker should 



23 


GLASSM AKERS 5 HAND-BOOK. 

possess sufficient technical knowledge to be able to tell, ap¬ 
proximately at least, what a recipe will do “ as soon as be 
looks it in the face. 7 ' One should always be able to deter¬ 
mine wliat a given recipe is worth—whether the base is suf¬ 
ficient, the flux well proportioned, the colorizer ample for the 
purpose intended, and, above all, whether, on the score of 
cost of production, the articles the metal is intended for will 
justify the investment. 

Cleanliness in the mixing room is the first consideration 
which should never be allowed to go unheeded. Thorough 
admixture, dependent on indifferent, careless and unwatched 
workmen, must ever continue to be one of the points insisted 
upon in all text books on glass manufacture, as long as hu¬ 
man nature endures, probably. 

There is now no secretiveness relative to mixes practica¬ 
ble. Analysis, at small expense, will reveal to all practical 
metal makers sufficient to base intelligent deductions upon, 
and enable one to reproduce all possible colors and combina¬ 
tions. 

In regard to recipes, it must be always borne in mind that 
batches used in single, clean and small pots, and in furnaces 
of such limited capacity or peculiar construction as enable 
one to minutely regulate the heat (both in the melting and 
fining process), must be altered and changed to suit different 
conditions encountered in large pots and large furnaces, 
which must be kept at a uniform high temperature in order 
to bring the metal around in time to employ a large working- 
force. 

The fine colors made abroad are produced mostly in small 
pots and small furnaces, the extent of heat and duration 
thereof can be readily controlled, and in most cases the metal 
can be readily worked out when at its best stage. W ith 
natural or artificial gas and the cold blast (for cooling the 
metal) in use in most American factories, however, we should 
be able, with intelligent manipulation, to rival the finest 


24 


GLASSMAKERS’ HAND-BOOK. 


color product of European manufacturers, and we do it in all 
cases where the necessary technical knowledge is employed. 

In the preparation of the batch careful calculation should 
always be made relative to the purpose for which metal is to 
be used. Glass to be made into articles requiring cutting 
should be made softer and less refractory than ordinary 
metal; vessels to be subjected to culinary use (hot water ex¬ 
erts a deleterious effect on glass), glass intended for retorts, 
carboys, for pharmaceutical purposes, or for use in chemical 
laboratories, should be compounded so as to offer the great¬ 
est resistance to the influence of acids. 


Such consideration should also be given to the composition 
of window and plate glass batches, in order to avoid, as far 
as possible, the objectionable discoloration which takes place 
in glass exposed to sunlight or atmospheric influences, atten¬ 
tion to which has already been called. 

Champagne, wine and mineral water bottles should be 
made of glass capable of resisting the pressure of at least ten 
atmospheres, from which it will readily be understood that 
the amount of sand in these glasses should be as high as pos¬ 
sible, for glass loses tenacity, strength and firmness, as well 
as polish and transparency, as the amount of flux used is in¬ 
creased. Besides, outside of the matter of fuel required to 
maintain the high temperature necessary to effect fusion, the 
simplest compounded, hardest glasses, are always cheaper 
than those rich in alkalies, and, consequently, softer glasses. 

Sand, soda, potash, lime, etc., are now furnished to glass- 
makers by supply companies, who exercise the greatest care 
and maintain a uniform high grade of product, that it seems 
quite unnecessary to caution against the use of impure ma¬ 
terials. Our sand is washed at the mines, freed from nearly 
all impurities, and contains such small quantities of oxide of 
iron, manganese and alumina that no special manipulation for 
eliminating these impurities are required. The former uni¬ 
versal practice of fritting has been almost entirely abandoned 


GLASSMAKERS’ HAND-BOOK. 


25 


in modern practice, though pre-heating the batch previous to 
filling in, for the purpose of driving out moisture, is a prac¬ 
tice that should be generally adopted. 

All “ guess work ” should be strictly forbidden in the mix¬ 
ing room, and all materials used sliouid be carefully weighed. 
Glass of uniform strength, color, density and firmness can be 
made only by the constant and never-varying adherence to 
the most minute exactness in the proportionate admixture of 
the materials. 

All materials should be reduced to a finely pulverized 
state—even to the cullet used. The finer all particles are 
the more surface they expose to the dissolving action of the 
fiux, and consequently enter into closer combination more 
readily; the batch fuses earlier, a saving of fuel is effected, 
time is gained, and the furnace need not be held at as high a 
temperature for so long a time as is the case where the mate¬ 
rials are of varying size, and consequently less intimately ad¬ 
mixed than is possible when they are reduced to a more 
finely pulverized condition. 

Machinery is fast displacing the old liand-shovel method of 
mixing, and where large quantities of batch are required not 
only effect considerable saving in labor cost, but, what is of 
greater importance, insure a uniform admixture of all mate¬ 
rials. Large lumps of cullet, solidified soda, salt cake and 
unslacked pieces of lime, which so often escape the indifferent 
workman, cannot escape the pulverizing power of the tireless 
mixing machine. That stratification in the metal, waviness, 
stones, and lack of homegenity are very often caused by im¬ 
proper mixing, and by insufficient pulverizing of the materi¬ 
als, is a matter that can be daily demonstrated to all who 
choose to observe, and trace effect to cause. 

In using salt cake carbon is added in the form of charcoal, 
or pulverized coke is added to the batch to burn out the salt 
water. 

The carbon is omitted where coloring is sought by metallic 


26 


GLASSMAKERS’ HAND-BOOK. 


oxides, as it would reduce them to the metallic state, in 
which they exert no coloring power on silicates. When it is 
sought to color salt cake glass the coloring oxides are not 
added until fusion has been effected and the carbon has been 
volatized. When batches are prepared Avitli sulphates of 
soda or potash, which contain hydrate of lime, the amount 
of charcoal should equal 8 per cent, of the sulphate used; if 
chalk or ground lime is used, between 6 and 7 per cent, of 
charcoal is sufficient; 10 parts, by weight, of charcoal may 
be substituted by 16 parts of coke or 26 parts of sawdust. As 
an excess of carbon colors glass amber, brown or black, ac¬ 
cording to the amount used, care should be exercised, and 
the bounds indicated above should not be materially over¬ 
reached. 

Gullet is generally added to ordinary batches in the same 
proportion as sand; it aids fusion, and prevents an undue 
volatilization of the alkalies. A large amount of cullet, how¬ 
ever, makes glass brittle, and of less firmness and elasticity 
than metal obtained from a regular fresh batch. The loss of 
material during the melting process by evaporation or 
volatilization depends on the composition of the batch, and 
generally averages about one-sixth of its weight. Thus 100 
pounds of 72 per cent, pure potash loses 22-80; 100 car¬ 
bonate of soda to 81-67 ; 100 Glauber salt, 56-81; 100 of pure 
saltpetre, 53-20; 100 red lead, 2-34; 100 of chalk or carbon¬ 
ate of lime, 44’00; 100 of hydrate of lime, 26 to 30. 

Charcoal and arsenic are completely consumed, leaving no 
trace ; manganese, on account of the small quantity generally 
used, completely vanishes. 

THE MELT. 


No pot ought to be charged with batch until the furnace 
and pots have reached a temperature sufficient to immedi¬ 
ately melt the charge, so that a perfect combination of the 



GLASSMAKERS’ HAND-BOOK. 


27 


materials shall take place, and to prevent the volatile ingredi¬ 
ents from escaping at a lower heat than is necessary to reduce 
the silica by an ordinary and uniform attack of the solvents. 
The full charge of the pots is generally done in three fillings, 
the loose batch necessarily occupying more space than the 
molten metal. Besides, it is easier to melt a pot of glass 
by thus dividing the charge ; a more even and uniform metal 
is secured, and waste of material by overflow and foaming is 
prevented. In open pots, where glass must be melted and 
fined at set hours for the blowers, the charges are usually 
dropped into the centre of the pot and are deposited in a cone 
or inverted Y shape, so as to expose the largest possible sur¬ 
face of batch to the action of the fire and facilitate the pro¬ 
cess of melting. The practice of bringing slow melting or 
corner pots around by the addition of extra quantities of soda, 
potash or cutlet, though extensively practiced, and often re¬ 
sorted to for the purpose of “ making up lost time ” after pot 
setting, is not to be commended, especially where uniform 
quality of window, plate, or bottle glass is a matter of impor¬ 
tance. 

In properly heated pots the melting of the batch proceeds 
from the sides of the pots centreward, from the bottom up¬ 
ward, and, to a less extent, from the top downward. The 
latter effect is noticeable in the fact that the cone-shaped 
peak of the filling is the last to vanish, and floats on the 
otherwise fluid mass. As the melt progresses moisture is 
evaporated, the gases and acids develop and exude, carrying 
with them a part of the batch, which deposit on the inner 
surface of the furnace or escape through the rings. The less 
refractory part of the batch is reduced, the fluid fluxes en¬ 
velop, attack and reduce the more refractory parts, the mass 
becomes agitated, and is slowly transformed to a fluid state. 

The second and third filling should not be added until the 
previous charge has been thoroughly reduced to fluidity, so 
that the bottom or base melting shall never be interfered 


28 


GLASSMAKERS’ HAND-BOOK. 


with; otherwise the batch, melting on the top, encases the 
raw materials with a fluid sheet, prevents the escape of the 
developing gases, and these, confined, gain power, and finally 
throw off the more fluid and volatile salts by foaming over 
the pots, and thus leave a large proportion of silica in a less 
fluxable condition than is desirable, and therefore unneces¬ 
sarily prolong the melt. 

Glass left in the bottom of pots after the blowing should 
be evenly distributed among other pots, so as to equalize 
materials and enable all pots to melt simultaneously. No glass 
should be allowed to remain in the bottom of the same pot 
more than a few days, as such remnants always gain in spe¬ 
cific gravity on account of the increased amount of alumina 
deposited from the sides of the pot and the ring, and is likely 
to become refractory, full of strings, striae and impurities. 
The best method is to dip out the pots regularly, fracture the 
remnants in water, and then evenly distribute the cullet among 
fresh batch, taking care not to allow any large accumulation 
of such inferior cullet. 


GLASS GALL (Salt Water.) 


Glass gall is composed of various substances which have 
failed to dissolve and combine with the silica during the 
melt. It consists generally of chloride of sodium (common 
salt), chloride of potash, sulphate of soda, lime, etc. It is an 
error to suppose that glass gall arises only from the use of 
salt cake, as some fair brands of soda have been found, upon 
analysis, to contain as high as 10 per cent, and over of sul¬ 
phate of soda. In such cases an addition of charcoal to the 
batch is advisable, so as to oxidize the glass gall. 

Being lighter than glass, salt water usually floats on the 
surface of the metal, but sometimes partially sinks to the 



GLASSM AKERS ’ HAND-BOOK. 


29 


bottom of the pot, and at other times distributes itself through 


the glass. 

From the analysis of Girardin the constituents of 
gall in different kinds of glass were found to be : 



CONSTITUENTS. 

Water, absorbed from the atmosphere... 

Sulphate of soda. 

Sulphate of lime. 

Chloride of sodium. 

Glass sand, alumina, phosphate of lime 


Window 

White 

Bottle 

Glass. 

Hollowware. 

Glass. 

1-65 

o-io 

1-00 

83-30 

90-51 

55-92 

10-35 

000 

25 00 

1-43 

0-04 

0.20 

3-a r > 

3-30 

47 77 

100-8 

99-95 

100-00 


The analysis of Richardson and Ronalds showed, in addition 
to the above results, traces of carbonate of soda and potash. 

Held in solution in the molten glass, the glass gall reduces 
the clearness and transparency of the metal, and divides it¬ 
self in white spots and specks and imparts a blneisli dullness 
to the glass. The impression that glass gall exerts an inju¬ 
rious effect upon the pots does not seem to be justified by the 
constituents, as shown in the above analysis. 

As glass gall escapes or is readiest driven off* when the 
glass is very fluid, it is best to keep the metal at a high tem¬ 
perature until the gall rises to the surface, from where it can 
be dipped oft* in ladles or burnt oft* by throwing moistened 
saw-dust or pulverized coal upon the surface of the metal. 
The old method of stirring up the metal with a stick of moist 
wood, the water and flame of which causes a fierce agitation 
of the contents of the pot, will always be found to be effica¬ 


cious. 


THE MELT—CRYSTAL AND FLINT HOLLOWAY ARE. 


The batch for crystal or flint glassware contains proportion¬ 
ately less silica than most other glasses, and being therefore 
more easily fusible, no such forced concentration of heat is 
necessary, especially as the methods of working out the glass 
do not require all the pots to be filled, melted, fined and the 











30 GLASSMAKERS* HAND-BOOK. 

furnace temperature lowered to enable the glass to be worked 
out, as is the case in the manufacture of plate glass, and in 
those bottle and window glass factories using pels. The 
structure of covered pots, and the method of enclosing them 
when set in the furnace, so as to expose the gatherer only to 
such heat as radiates from the furnace and the pot mouth, 
requires no lowering of the furnace temperature while the 
metal is being worked out, and hence the process of work¬ 
ing out some pots while the melt is being made in others is 
rendered possible. 

The closing or u stoppering ” of the pots, and taking- 
down of the stoppers, enables the regulation of the tempera¬ 
ture; raises the heat of the pot during the melt or lowers it 
to cool the glass for working. Besides, the general use of the 
cold blast in all properly equipped press and bottle houses 
now enables the speedy chilling of glass in the pot for work¬ 
ing purposes that little description of long approved methods 
or processes is required. 

In the manufacture of line colored glass, where so much 
depends upon a proper and minute manipulation of heat, the 
large American pots and furnaces offer the greatest difficul¬ 
ties for making uniform shades, for, as a rule, the tempera¬ 
ture of the pot contents cannot be sufficiently controlled by 
simply stoppering or unstoppering the pot. 

Not that we undervalue the importance of stopper-adjust¬ 
ment in all batches in which oxidizing or reducing agents 
must be used to effect desirable results; but we cannot but 
express the opinion that in the making of all sensitive 
colors, where line shading and uniformity is a chief consider¬ 
ation, the small furnaces and pots used by European glass- 
makers are more easily controlled, and are conducive to 
better results. 

The use of small “ monkey " pots for making of line colors 
where quality is of more importance than quantity, approaches 
closely the approved method pursued by the color makers in 


glassmakers’ hand-book. 


31 


the old world, and with properly perforated jack brick to im¬ 
provise a bench for the small pots, through the openings of 
which a cold blast can be readily applied to the bottom and 
sides of the pot, there is no reason why we should not be 
able to obtain the best possible results in the manufacture of 
line colors. 

FINING, OK STANDING OFF. 


Though the furnace temperature is kept at a very high 
heat during the melt (no rule for which can be given, on ac¬ 
count of variations in furnaces and batch composition), the 
glass only gradually becomes transparent and plain, the 
opacity being due to bubbles of air or gas and to the lime 
and earthy impurities which do not as easily yield to fusion 
as other ingredients of the batch. 

The object of the fining, which is the last process of the 
melt, is the removal of these bubbles, blisters and seeds by 
the subsidence of the heavier particles to the bottom and the 
escape of the gas at the surface. For this purpose the molten 
glass must be brought to and held at the highest possible 
heat consistent with the safety of the pots, for some hours, 
for it is only in the most fluid state that the thousands of in¬ 
finitesimal seeds throughout the mass are readiest driven to 
the surface of the metal. 

When the metal has become plain, clear and transparent, 
the furnace temperature is lowered, so as to bring the glass 
from a state of nearly perfect fluidity to that viscid and plas¬ 
tic condition necessary for working. In factories equipped 
with cold blast the soft glass is very readily brought to a 
proper state for working by introducing a stream of cold air 
into the pot, if required for working, as soon as the glass is 
sufficiently plain. 

The reactions which take place in the pot are very easy to 
understand. For instance, if the silicate has been mixed 
with carbonate of soda and carbonate of lime, the silicate, at 



32 


GLASSMAKERS’ HAND-BOOK. 


a high temperature, seizes on the soda and lime, and the car¬ 
bonic acid is disengaged. In the same manner, if silicate 
lias been mixed with carbonate of potash and minium, this 
last returns to the state of massicot, and the silicate then 
combined with it and the potash. There is, therefore, in 
this case, first a disengagement of oxygen, then an elimina¬ 
tion of carbonic acid. 


These evolutions of gas, which constantly accompany the 
production of glass, explain the presence of the air bubbles 
already mentioned as so frequently observed in the vitreous 
mass. To expel these it lias been stated that the tempera¬ 
ture must be raised very high, that the glass may become 
quite fluid. But as the potash and soda may lie volatilized 
at this high degree of heat, one is obliged to introduce into 
the compositions much more potash and soda than the glass 
is intended to retain. 


This elevated temperature is also necessary in all cases 
where impure alkalies are used. The presence of the chlo¬ 
rides, and even that of the sulphates which melt without mix¬ 
ing with the glass, would occasion in the latter a multitude 
of white and opaque nodules disseminated through its mass. 
At a high heat both of these matters, being lighter than the 
glass, rise and float on the surface, constituting the principal 
portions of the glass gall above alluded to. It must be 
stated, however, that ever since the salts of soda have been 
sold at a low price,.and are consequently generally used, very 
little glass gall has been produced in the manufacture of the 
ordinary kinds of white glass ; but in bottle and window 
glass manufacture this impurity often occurs, because crude 
sodas and salt cake are employed. 


FAULTS IN THE GLASS. 


If there is one thing more than another that should be 
driven from the glass factory, it is that convenient, ever- 



GLASSM AKERS* HAND-BOOK. 


33 


present, all-excusable and indefinable jack-o’lantern called 
" Luck ’—that scapegoat for so many sins of omission and 
commission. 

.Tlieie may be such a thing as chance and luck in other 
vocations and professions, but there is none in glassmaking. 
Indeed, here nothing should be left to chance, and, where 
such a rule is insisted on, there is not likely to be any luck 
whatever, and, least of all, “ bad luck.” 

Faults in the glass are faults of somebody who has either 
furnished, bought, improperly mixed or partially melted the 
materials. But if the materials used are as they should be 
for any given glass, then certain results must follow certain 
causes, definite and traceable. Faults in the glass are al¬ 
ways the result of lack of judgment, ignorance, carelessness, 
lack of proper precaution, or of not doing the right thing at 
the proper time. When there are faults in the glass some¬ 
body does not understand his business, or some one has not 
attended to his duty. 

Thus, glass gall is the result of impure materials, or of 
wrong proportions in the batch. To get rid of it, however, 
during the melt, and in time for the blowing, is the business of 
the master teaser, and, when glass gall or salt water remains 
disseminated through the metal, he has not taken proper pre¬ 
caution in time T:o drive it off by such methods as it is his 
business to know, and his duty to resort to at the right period 
of the melt. If glass gall has resulted from improper, insuf¬ 
ficient or careless mixing, the fault lies with the mixer; if of 
improper proportions, with the manager or metal maker; 
or, if the materials are impure, with the purchaser or manu¬ 
facturer of them, primarily. There is a cause, and an am¬ 
ple one, for all faults and defects; but there is no “ luck.” 

Waves and striae in the glass result from a lack of home- 
genity and uniformity of the molten mass; and such lack 
of even density as the result of perfect fusion and thorough 
admixture of the pot contents are directly traceable to cer- 


t 


34 


GLASSMAKERS* HAND-BOOK. 


tain causes. Prominent among these may be named large 
lumps of cullet, filled in too late to receive attack or be sub¬ 
jected to the agitating action of the solvents and more vola¬ 
tile ingredients; too large a proportion of harder, ill-assorted 
and indifferent cullet; insufficient pre-lieating of the furnace 
and pots previous to the first filling; filling in before the pre¬ 
vious charge had sufficiently fused; the use of insufficient 
proportions of nitre, arsenic, saltpeter; or, in flint glass, an 
undue preponderance of lead, the specific gravity of which is 
three times as great as the other materials of the batch. In 
all these cases the way to avoid the “ faults ” is, first, to 
avoid the causes; second, to make use of such remedies in 
time as experience and common sense dictate and suggest. 
The use of a moist potato; deep insertion of arsenic, etc., or 
stirring contents with a moist wooden pole while the mass is 
in a very fluid state, are among the best practical expedients 
advisable. 

Other faults, defects and imperfections occurring in glass 
are so well known, and are so easily traceable to their cause 
and root, as to make prolonged and minute description and 
instruction seemingly superfluous. The high temperatures 
to which furnaces can now be urged and held, resulting from 
improved construction, a wise division of expert labor and a 
large investment of scientific and technical knowledge of fur¬ 
nace construction by careful, painstaking and reputable spe¬ 
cialists, as well as the high efficiency attained in the manu¬ 
facture of melting pots and clay manipulation, and the 
superior natural or manufactured gas fuel applied to mod¬ 
ern American glass manufacture, has enabled glassmakers to 
obviate so many of the defects formerly so frequent and in¬ 
surmountable as to render detail quite gratuitous. 

Slacks, formerly so frequent in bottle and window glass, 
caused by fumous deposits of the batch, or resulting from 
vitrified portions of iron in sandstone furnace caps have 
been almost entirely obviated by improved construction of 


GLASSM A K E RS ’ H A N D-BO() K. 


35 

the rings, or the introduction of silica brick or Dinas blocks 
in modern furnace construction. 

I breads, strings, gatherer’s blisters, dust imperfections, etc., 
and their causes are so well known, and so easily avoided, 
that we pass them over to the general domain of proper fac¬ 
tory management and intelligent workmanship. 

The best rule, however, is to avoid the occurrence of emer¬ 
gencies by wise, timely precaution and careful attention to 
details. 

Managers and superintendents ought to make no excuses 
themselves for faulty glass, and they should accept no excuse 
from either teaser, mixer or in-lillers. Explanations, how¬ 
ever, are always in order. Intelligent inquiry; an honest 
search for the real cause of bad results; and fastening the 
blame only on the thing or person at fault, after indisputable 
certainty has been arrived at, are the best and most lasting 
of all remedies. 

FURNACES AND POTS. 


Added to what has been already said about improved fur¬ 
nace building and pot construction, departments which, 
owing to modern division of labor, no longer fall, as a rule, 
into the province of the glassmaker, strictly speaking, atten¬ 
tion should perhaps be called to the rapid adoption of the 
tank furnace in the United States during recent years. As 
in so many other important departures from the old and 
foot-worn paths in glass manufacture, European glass manu¬ 
facturers have preceded us by many years in the adoption of 
the tank system. 

Continuous and intermittent tanks, large and small, have 
of late come into use ; have so fully passed the experimental 
stage, and demonstrated their “ right to be ” in the economic 
struggle of progressive development, that a few words about 
them seems to be in place. In the manufacture of cheap col- 



36 


GLASSMAKERS’ HAND-BOOK. 


ored glass, for small articles, novelties and common" glass¬ 
ware, bottles, flasks and prescriptions, both flint and green, 
small intermittent tanks have proved successful beyond a 
doubt. In fine flint tableware and lime glass chimney man- 
facture, however, the number of abandoned experiments up 
to this time largely outnumber the successful cases of pro¬ 
longed adherence; the main difficulty seeming to be that the 
color cannot be held until the glass is worked out. This re¬ 
lates, however, only to intermittent tanks, and results mainly 
from the fact that those tanks presenting the above-named 
defect have thus far been mainly u top melters,” and the bot¬ 
tom glass, as a rule, is colder, stiffer, more refractory, on ac¬ 
count of subsideary deposits of impurities and alumina from 
the furnace blocks, and, what seems of more importance, be¬ 
cause of a lack of confinement of so large a surface mass of 
molten glass to the agitating action of the saltpeter or arsenic. 

In the manufacture of window glass the large continuous 
tanks used in England and Belgium, and notably the various 
tanks of the Chambers & McKee Company at Jeannette, Pa., 
which in a few years have not only overcome the prejudice and 
antipathy of the window glass gatherers and blowers, but 
have turned out, continuously and regularly, as clear, trans¬ 
parent and faultless glass as has ever been made, and far su¬ 
perior to much that has ever been or is yet made in pots. 
The saving effected in fuel (there is no need of cooling off the 
furnace for the blowing and reheating for the melt) the im¬ 
proved and cheaper methods of handling and charging the 
batch on a large scale, and the increased and incessant out¬ 
put of metal, all commend the tank system from an economic 
point of view. It must be remembered, however, that large 
plants, such as those under consideration, are only possible 
with an aggregation of ample capital, and yield profit only 
under the best technical management, with minute attention 
to every detail. 

* 

The very features which seem to offer the greatest diffi- 


GLASSM AKERS 7 HAND-BOOK. 


37 


culty to the successful operation of the intermittent tanks 
appear to be an advantage to the continuous tank furnace. 
The incessant action of the alkalies on the sides and bottom 
of the tank at first eat out and destroyed the furnace blocks 
very rapidly. Siemens, however, early introduced air flues 
along the sides and Under the bottom, so as to chill several 
inches of the glass on the.side walls and bottom of the tank, 
and thereby not only reduced the deleterious action of the 
glass on the furnace, but also reduced the deposit of alumina, 
which renders glass impure and refractory, to a minimum, 
so that in reality a clear and better glass is theoretically and 
practically obtainable in a continuous tank than is possible 
in a pot furnace. 

Tank furnaces consist of a charging chamber, a melting 
and refining apartment, and a blowing or working compart¬ 
ment. The acid vapors and gases released in the charging 
chamber are mainly carried off through a stack, and injuri¬ 
ous effect on the furnace thereby obviated. 

In window glass manufacture no general departure has 
been made in furnace structure for many years, though in 
several factories regenerative furnaces have been introduced 
with very satisfactory results. Such furnaces obviate the 
difficulties heretofore presented in maintaining a suitable 
heat during the blowing, without smoke, flame or fuel impu¬ 
rities interfering with the workmen or the metal, especially 
in tank furnaces, and in the window glass and bottle manu¬ 
facture where open pots are mostly used. 

The form of the old style furnace, retaining the bench and 
deep fuel space for the “ coal brace,” makes pot setting difficult 
and laborious, and endangers the safety of the green pots. The 
success of the round furnace used at Chambers’ Pittsburgh 
factory in 1886, making pot setting as safe and easy as possi¬ 
ble, and allowing the use of the low-wheeled, pronged car¬ 
riage, which grasps the pot under the bottom and does away 
with the liability to strain the pot during the process of set- 


GLASSMAKERS J HAND-BOOK. 


38 


ting by holding it at the upper edge with clumsy iron hooks, 
should have led to a more general adoption of the round 
form, so long and successfully used in flint glass manufac¬ 
ture, and offering many advantages over the old square 
shape. 

We desist from further detailed description, for the reasons 
stated at the beginning of the heading, and refer readers de¬ 
sirous of pursuing the subject further to the list of special 
works, which will be found in the appendix. 

OVENS ANI) LEERS. 


Ovens and leers used in all branches of glass manufacture 
have undergone so little change for many years, and modern 
construction has left so little room for improvement, that the 
same reasons why space and time need not be taken up with 
minute descriptions, enumerated under ftie head of Furnaces 
and Pots, applies equally to the present subject. 

In window glass manufacture the tendency has been favor¬ 
able to smaller flattening ovens, and the four stone oven and 
Tondeur rod leers have effected such a saving in breakage, 
delivers the glass much earlier than was formerly possible, 
anneals the sheets so satisfactory, and does away with the 
costly and cumbersome iron cars, that it has been generally 
adopted in the United States. The small ovens have been 
found best on account of their working slower, and cylinders 
are not “ laid in ” so early and exposed to the flame as 1 oilg¬ 
as in the old eight-stone ovens. There three cylinders were 
always in the oven ; one on the stone before the flatten er, the 
second on the “ layer-out's r stone, and the third upon the 
laying-in “ saddle.” If from any cause the flattening of a 
sheet was unduly prolonged, the other two cylinders were 
kept exposed to the oven flame too long, and their surface 
polish often injured. In small ovens this feature is largely 
obviated, as only two cylinders can be placed into the oven, 



GLASSMAKERS’ HAND-BOOK. 


39 


and the second one is not “ laid in ” until the flattening of 
the sheet preceding it is nearly completed. Another advan¬ 
tage is that one flattener only is required to operate the oven, 
and as he wipes the stone, lays out his own cylinder, and 
orders the laying in of cylinders, the responsibility of bad 
work cannot be evaded as formerly, and better work is the 
result. 


In flint glass leers no radical departures from old methods 
have been made during recent years, though many improve¬ 
ments have been made in superior construction and arrange¬ 
ment. The main feature that requires the attention of in¬ 
ventors in regard to leers for flint glassware is some improve¬ 
ment to get rid of the labor required to bring the empty pan 
from the leer end to the mouth and adjust it. Nearly as 
much time is required in this bringing back of the pan as 
there is in emptying it of ware. A leer with pans adjusted 
to long links of an endless chain, or to a cable, would reduce 
the cost of leer attendance nearly one-lialf, and it is a matter 
of surprise that no such improvement has been introduced 
before now. 

In bottle and small hollowware manufacture the late Mr. 
August Weyer introduced an improved annealing oven at 
Celina, Ohio, which is likely to be generally adopted. The 
oven is constructed much after the old style in shape and 
size, but the front and back are provided with wider open¬ 
ings, through which a large sheet iron box is inserted and 
withdrawn. The box is provided with a door at the end, and 
fills the front opening of the oven when placed into position 
on the oven floor. Through this door the ware is piled into 
the box. When full the box is closed and removed through 


the opening at the back by means of a forked carriage (simi¬ 
lar to the pot setting carriage used in flint glass works), and 
is taken out direct to the packing room. The ware is packed 
direct from box, and thus the labor formerly required to 
empty the ovens and rattle and break more or less ware by 


40 


GLASSMAKERS* HAND-BOOK. 


wheeling it over a rough floor on ware boards is entirely done 
away with. 


From this idea there is likely to be developed other im¬ 
provements, and it is only a step further in the line indicated 
by Mr. Meyers' departure, which shall give us large cars, made 
of heavy iron, so as to retain sufficient heat for a proper an¬ 
nealing of the ware, which may be run into ovens or prop¬ 
erly constructed enclosing walls, be filled with ware and run 
direct to the packers or to the ware room or stock sheds. Fur¬ 
ther improvements naturally suggest themselves, such as 
hinged top doors or lids for the cars, or arched wall enclo¬ 
sures, heated at a lower temperature so as to insure a gradual 
cooling of the cars and their contents, all of which will effect 
a great annual saving in the cost of manufacture. 


WINDOW GLASS. 


There have been many attempts made to improve the 
flattening process, and the inventors and manufacturers of 
Belgium, France, Germany and England have introduced 
various methods, which have largely met with very indiffer¬ 
ent success. Even with the most perfectly blown cylinders 
there is always a natural inherent and structural defect in 
blown sheet glass, because the inner is smaller than the outer 
surface, and there is a molecular crush and strain takes place 
in the flattening process which makes the production of per¬ 
fectly plane sheets very difficult. Besides, the fine fire polish 
of the glass deteriorates in the flattening oven, often because 
of an impinging flame, from tool marks, an unclean or charred 
flattening block, flying particles of dust, etc. Efforts 
have been made to construct ovens so as to obtain a radiat¬ 
ing, flameless heat, and where the gas supply can be regu¬ 
lated, or the flattening apartment hotly flashed at intervals 
before inserting the roller, this method has given good re- 



GLASSM AKERS’ HAND-BOOK. 


41 


suits, but it is necessarily slow and requires care and close 
attention on the part of the flattener. 

There have been repeated attempts made to improve the 
flattening stones, structurally, as demand for large sizes of 
double strength sheets, owing to the greater cost of plate 
glass, has wonderfully increased during recent years. Some 
factories now having stones as large as 55x80 inches, it has 
been found difficult to keep clay stones of such dimensions 
from warping, scaling or crazing on the surface. Hence 
English manufacturers have constructed stones of graphite, 
which hold a very high surface polish, and are said to have 
given good results, though the material is costly. 

Iron plates, perforated, and cooled with water, have been 
tried in Germany, but were abandoned on account of undu¬ 
lations resulting from unequal contraction and expansion. 
Tscheuschner* is authority for the statement that the iron 
plates introduced by Moritz described in the Sprechsaalf, have 
given the most satisfactory results. These cast iron plates 
were planed and polished on the surface and filled in below 
with a bedding of clay, to retain an even heat, and are said 
to have preserved a smooth surface and impartial greater 
brilliancy and a higher polish to the flattened sheet than it is 
possible to obtain on clay stones. This subject is worthy the 
attention of American manufacturers, and the suggestion of 
the inventor to increase the polish by nickel plating the cast- 
iron plate may prove of practical value. 

The manufacture of blown ribbed, fluted and kinkled cyl¬ 
inder glass in various colors lias until lately been carried on 
to a very small extent in the United States. Though it 
should be treated of under the head of window, sheet or cyl¬ 
inder glass, the process of manufacture differs so little from 
• tl^it of window glass as to render description unnecessary. 
The colors used will be found under the head of colored 


♦Handbucli der Glasfabri Ration, page 405. 
fSprechsaal 1882, No. 885. 



42 


GLASSM AKERS’ HAND-BOOK. 


glass, and need not therefore be detailed here. The flutes, 
ribs or other undulations are imparted to the ball after being 
blown in the block, as in window glass, and, after being- 
heated, the ball is inserted into a mold or former, which is 
provided with the desired pattern, incised or projecting. 
This mold must have the pattern or figure (flutes, ribs or 
kinkles) to an exaggerated degree, as during the subsequent 
elongation of the ball they are considerably decreased. 

Sometimes the flutes or other designs are imparted to the 
plain blown sheets under suitably incised pressure plates 
while the glass is in pliable state, or on iron plates or flatten¬ 
ing stones provided with flutes or undulations. 

The application of improved machinery, however, seems 
to point to a very large expansion of the manufacture of cast 
and rolled glass, in which casting tables and rolls may be 
made to contain the most elaborate patterns, and inasmuch 
as the demand for stronger and heavier glass, especially in 
large sheets, is constantly growing, the production of blown 
figured glass may not be able to long survive such competi¬ 
tion. 

WINDOW GLASS RECIPES. 


AMERICAN WINDOW GLASS. 

(Salt cake glass, with small addition of soda.) 



1 

2 

3 

4 

5 

Sand. 

. 100 

100 

100 

100 

100 

Salt cake. 

. 32 

84 

40 

38 

40 

Ground lime. 

. 82 

82 

88 

36 

40 

Soda. 

. 6 

5 

4 

4 

8 

Arsenic. 

2 

2 

1 

2 

2 

Pulverized charcoal. 

. 0 

7 

8 

5 

6 


6 

7 

8 

9 

to 


— 

— 

— 

— 

— 

Sand. 

. 100 

100 

100 

100 

100 

35 

Salt-cake. 

. 84 

86' 

88 

42 

Ground lime. 

. 80 

84 

36 

38 

34 

Soda. 

. 4 

7 

5 

8 

5 

Arsenic. 

. 1 % 

2 

Vi 

2 

2' 

Pulverized charcoal. 


0 

r* 

7 

734 

6 

















GLASSM AKERS’ HAND-BOOK. 
(Salt cake glass, without soda.) 


43 


Sand. 

11 

12 

13 

14 

15 


100 

100 

100 

42 

100 

Salt cake. 


38 

35 

43 

Lime. 


30 

34 

40 

34 

< ’harcoal. 


0 


0 


Arsenic. 


1 

2 

2 



16 

17- 

18 

19 

20 

Sand...-r.. 


100 

100 

100 

100 

Salt (take. 


38 

30 

33 

40 

34 

30 

Lime. 


31 

31 

Charcoal. 

3 

4 

0 

4 

o 

Arsenic. 

. 34 

2 

1 


1 


>2 


It will be seen at a glance at the above recipes that the 
first ten contain a small addition of soda, varying from 4 to 
8 lbs., to the 100 of sand. The use of soda increases the cost 
of the glass but aids fusion, and will sometimes be of advan¬ 
tage in emergencies. The good results obtained from the use 
of salt cake alone, however, the lower (tost of it, as well as 
the greater brilliancy and polish, and greater resistance and 
hardness, should make the presence of the imported soda 
cask about an American window glass factory a real curi¬ 
osity, as the use of soda at this late day is to be ascribed 
solely to the conservatism and adherence to the u good old 
way " on the part of window glass makers. 

Of course it will be understood that any of these formulas 
can be changed to suit the ideas of managers or manufactur¬ 
ers. The only thing to bear in mind is that as the quantity 
of lime is reduced, the fusibility of the glass increases; but 
that it suffers in hardness and the power to resist atmos¬ 
pheric influences, and that the more sand that can be melted, 
the cheaper the product necessarily will be. The above 
recipes are known to yield glass that is reasonably cheap and 
still produces good working metal. 

The proportions of charcoal and arsenic may also be 
varied, but only within certain limits. Arsenic is used to 
decolor, and manganese or oxide of nickel may lx 1 substi¬ 
tuted, though the use of manganese, for reasons stated else¬ 
where, is not commended. 















44 


GLASSMAKERS’ HAND-BOOK. 


Cullet is usually added in the same proportions as sand by 
weight. It should be clean, and if in lumps, should be 
broken finely so as to assimilate more readily with the batch. 
Over-charges of cullet should be avoided where uniformity 
and quality of product is aimed at, and it should always be 
remembered that the best compounded glass is generally that 
having the least of cullet admixed. 

In order to give the widest range of view for practical pur¬ 
poses, as well as for comparison, we add the most reliable 
foreign recipes for window and crown glass: 


BELGIAN WINDOW GLASS. 



1 

2 

3 

Ar 

5 

Sand. 

. 100 

100 

100 

100 

100 

Salt cake. 

. 36 

38 

35 

40 

42 

Carbonate of lime. 

. 40 

38 

32 

36 

38 

Charcoal. 

. 2 

134 

234 

4 

6 

Cullet. 

. 100 

100 

100 

100 

100 


FRENCH WINDOW GL 

ASS. 



Sand. 


... 100 

100 

100 

100 

Salt cake. 


... 35 

40 

42 

38 

Lime. 


... 25 

35 

34 

36 


1.34 


Charcoal. 

Manganese. 6 oz. 

Arsenic. 1 

Cullet. 100 

GERMAN SHEET GLASS. 

Sand. 100 

Soda. 28 

Lime, hydrate. 27 

Nitrate of soda. 2 

Charcoal. 8 

Arsenic. 1 

Manganese... 34 


8 

5 

2 

100 


oz. 


100 

82 

80 

8 


134 

120 


100 

88 

82 

4 

5 


2 

110 


100 

40 

35 

6 

6 

9 


34 


BOHEMIAN (SOLIN) GLASS. 

1 


Sand... 100 

Potash.. 45 

Lime (hydrate). 12 


Arsenic. 

Manganese. 
Cullet. 


2 

T 

100 


2 


Sand ... 
Potash 
Salt. 


100 Lime (hydrate) 

40 Arsenic. 

5 Cullet. 



3 


Sand. 

Potash.... 

Saltpeter 


100 

40 

2 


Lime (hydrate) 

Arsenic. 

Cullet. 


12 

34 

100 

















































GLASSMAKERS’ HAND-BOOK 


45 


SEMI-WHITE SHEET GLASS. 


The manufacture of semi-white and white sheet glass has 
not as yet been engaged in to any extent in the United States. 
The vast amount of thin sheet glass used in photography, as 
well as the largest part of the shades, blown, bent or curved, 
for the various uses they are put to as a protection for art 
work, taxidermy, wax work, flowers, etc., are nearly all im¬ 
ported. We deem the matter of sufficient importance to add 
the best formulas for making a reasonably cheap and work¬ 
able glass in semi-white and white. In order to avoid repeti¬ 
tion, the amount of manganese, arsenic, nitre, saltpeter, for 
oxidation or decoloring purposes, are not repeated with each 
recipe, as the usual proportions given with former recipes 
are applicable here, and may be varied to suit any special 
case. It should be noted, however, that where the use of 
burnt, slacked lime is resorted to, often as a matter of con¬ 
venience, the pot contents are not agitated, or so violently 
boil or “ work '* as in cases where 4 ground, raw limestone is 
used. Hence, to secure an even and uniform texured glass, 
the use of arsenic, nitre, saltpeter, etc., must be resorted to 
so as to secure thorough admixture of the pot contents. 
Ground, raw lime gives uniformly better results than burnt 
slacked linn 4 , and should always be employed where practi¬ 
cable. 

SEMI-WHITE SHEET GLASS. 

1 


Sand. 100 

Potash. 50 


Salt cake. 


10 


Charcoal. 1 

Slacked lime. 14 

Gullet. 100 


Sand.. 

Sulphate of potash. 
Salt cake. 


100 

40 

8 


Glass gall. 2 

Charcoal. g 

Cullet. 100 


Sand. 100 

Salt cake.35-45 

Carbonate of lime.30-38 


Charcoal. 2%5-3 

Cullet. 100 


*100 of sulphate of potash is equal to 81 salt cake; 100 salt cake equals 122 of 
sulphate of soda. 























46 


glassmAkers’ hand-book. 

# 

4 


Sand. 

Salt cake. 

Common salt 


100 

BO 

13 


Carbonate of lime 

Charcoal. 

Gullet. 


5 


30 

3 

100 


Sand. 



100 

Carbonate of lime. 


... 32 

Salt cake. 



15 

Charcoal. 


2-s 

Baryta (heavy 

spar). 

. 

28 

Cullet. 


... 100 


SEMI-WHITE, WITH SALT CAKE. 





1 

2 

3 4 

5 

6 

Sand. 


. 100 

100 

100 100 

100 

100 

Salt cake. 


. 55 

44 

36 40 

38 

42 

Charcoal. 


3 

6 

4 3 


6 

Lime. 


. 50 

32 

28 32 

33 

35 

Soda. 


6 






7 



8 



Sand 



100 

Sand... 


... 100 

Salt cake. 



50 

Salt cake. 


... 45 

Ground lime.. 



20 

Pulverized coal. 


3 

Charcoal. 



3 

Carbonate of lime. 


... 18 


9 



10 



Sand. 



100 

Sand. 


... 100 

Salt cake. 



30 

Salt cake. 


... 35 

Ground lime.. 



*30 

Lime. 


... 28 

Charcoal. 



3 

Charcoal. 


4 



WHITE 

SHEET GLASS. 



Sand. 

* 


100 

Lime. 


.... 26 

Potash. 



60 

Cullet. 


.... 100 


Sand.. 
Potash 
Lime... 


2 

✓ 

, 100 Saltpeter. 
45-55 Gullet ....It 
32-40 


2 


100 


Sand. 100 

Salt cake. 35-40 

Carbonate of lime.30-35 


Charcoal. 2-5 

Gullet. 100 

Arsenic.. 1 


4 


Sand. 100 

Salt cake. 36 

Carbonate of lime. 40 


Charcoal. 3 

Arsenic. 2 

Gullet. 100 


5 


Sand. 

Salt cake 
Potash ... 


100 

32 

8 


Ground lime 

Charcoal. 

Cullet. 


CROWN GLASS. 

1 


38 

4 

100 


Sand. 

Red lead 
Potash ... 


100 

75 

35 


Saltpeter 
Cullet. 


4 

100 






















































































CtLASSMAKERS’ HAN I)-B()<) K. 


47 


Sand ... 
Potash 
Soda. 


Sand .. 
Potash 
Borax. 


2 


100 Chalk... 
80 Arsenic 
16 

3 


100 Red lead... 
40 Manganese 


8 

0.5 


o 

0.2 


ARCHITECTURAL GLASS. 


The blown or cast glass, known under various names as 
autique, cathedral, ondoyant, or, collectively, architectural 
glass, the manufacture ol which has begun to assume such 


proportions as certainly entitle it to consideration, shall be 
briefly noticed. 

The recipes for colors used are the same as those found 
under the head of Colored Glass, to which the reader mav 

turn. 


The method of producing colored, opaque tiles, for flooring 
or wainscoating, heavy colored sheets for screens, partitions, 
transoms, etc., will be readily understood by all practical 
glassworkers; the pressing of the former being similar to 
that of tableware manufacture, while the latter accords with 
the process of casting and rolling, previously referred to, pur¬ 
sued in the manufacture of plate glass. 

The sheets now made are very large, some fine colored 
cast plates being 40x60 inches, and the method of casting is 
favorable to the production of still larger sizes, if desired. 

In small factories the different colored glass is ladled from 
adjoining pots, poured onto the casting table, and the colors 
admix and interlap in the most intricate and novel forms by 
the rolls being run over the mass. Where sheets are to be 
cut into small pieces of various curves, angles, shapes, for 
fine color designs, and where the artist and glazier must 
have in view the proper light effect and tone, as well as 
search for shadings and colors that must flow into each 
other and harmoniously blend, it will be seen that a properly 















48 


GLASSMAKERS’ HAND-BOOK. 


balanced and well compounded glass is of the utmost impor¬ 
tance. Hence the batch should be so compounded that too 
much waste shall not result through breakage from brittle¬ 
ness, hardness, or lack of homegenity in different glasses ad¬ 
mixed for color effect. The same care should be exercised 
in this branch as is necessary in making glass for casing, as 
there is here the same liability to molecular strain if glasses 
of different composition and texture are admixed. 

In antique glass some very peculiar effects are produced, 
and the blisters, go noticeable in ancient glass, are very 
closely imitated. Color is not always a prime consideration, 
except where a large amount of some particular shade is to 
be used in the same building, or where tints are to be closely 
matched. For this reason a color scale should be kept, 
showing all the colors manufactured, and the composition of 
each tint and color should be kept on record at the factory. 

In fine art tile some very commendable work has been 
done during the past few years, and this branch of glass 
manufacture seems destined to largely develop, especially if 
the necessity of matching the fine artistic shades and finished 
figure designs made by American clay tile manufacturers is 
not lost sight of. 

In the production of fine colors and tin 1 variety of novel¬ 
ties introduced into art windows, especially in opalescent 
effects, American artists have made such startling progress 
during recent years as to call forth the praise and commend¬ 
ation of one of the most careful and observing experts, who 
recently contributed a series of very able articles on the 
u Manufacture of Opalescent Glass in flu* United States” to 
“ Diamant." 


Diamant,” ]890. 


PLATE GLASS. 


The formulas used in the early manufacture of plate glass 
contained potash and soda, and salt cake was but sparingly 




GLASSM AKERS' HAXI)-B()OK. 


49 


and cautiously used until a much later period. These softer 
glasses were most suitable to the old furnaces, and the com¬ 
parative crude and primitive machinery used for casting* re- 
quired a glass of great fluidity. 

The oldest batches were composed of: 

i 


Sand. 

Soda. 

Potash (refined) 
Lime (hydrate). 


100 

33 

6 

12 


Manganese 
Saltpeter... 
Cullet. 


0.5 
2 — 
100 


Sand. 

Soda (refined).... 
Potash (refined( 


2 


100 Lime (hydrate) 
30 Cullet. 


16 

100 


3 


Sand. 

Soda (pure). 

Lime (hydrate).. 


100 Saltpeter... 
35 Manganese 
20 


34 


Muspratt states (1860) that the use of salt cake had not 
been generally adopted in plate glass manufacture at that 
time. Improved furnaces, competition, and a desire to pro¬ 
duce glass of greater resistance to atmospheric influence, how¬ 
ever, forced the use of cheaper materials upon manufacturers, 
and previous to 1800 we find salt cake being gradually 
adopted. The American practice was hampered for many 
years, but the introduction of Regenerative furnaces and 
the use of natural gas led to a more general use of salt cake. 

The early and later (1880) recipes used at the St. Gobain 
works are given by Henrivaux : 


Old practice. 


Silica. 771 

Lime. 00 

Soda. 16 

Alumina and oxide of iron 6 


I 


iater practice. 
721 
157 
22-2 
trace 


The later practice shows a large increase in lime and a re¬ 
duction in the amount of potash used. 

Graeger gives the following recipe for a salt cake batch: 


Sand. 

Salt cake. 

Carbonate of lime 


100 

35 

26 


Charcoal.... 
Saltpeter... 
Manganese 


25 

2 

0-25 
































50 


GLASSMAKERS’ HAND-BOOK. 


From the analysis of Jaeckel, it appears that the formula 


as given: 

Silica. 

Lime. 

Soda. 

Alumina.. 


ANALYSIS. 


.72.31 would require Sand. 

14.96 Lime. 

.11.42 Salt Cake 

0.81 Charcoal.. 

- Arsenic.... 


99.50 


100 

, 38 
, 38 
2.5 
0.4 


Which corresponds within a fraction to the formula stated 
by Henrivaux, to be in use at the St. Gobain works. 

Without desiring to repeat and duplicate recipes, it may 
be well to point to the formulas in use in different European 


Plate Glass Works, showing a very close adherence to pro¬ 


portions approved by experience : 



Montlucon. 

German. 


(Henrivaux.) 

(Henrivaux.) 

Silica. 

69.3 

70.27 

Lime. 

15.8 

15.86 

Soda. 

13.4 

13.66 

Alumnia and Oxide of Iron.... 

1.5 

0.21 


St. Gobain. 
(Pelouze.) 
72.1 
15.5 
12.4 


100.0 100.00 100.0 


PLATE GLASS EECIPES. 


12 3 4 5 


Sand. 100 100 100 100 100 

Lime. 37 38 36 34 35 

Salt cake. 37 40 38 35 38 

Charcoal. 2.5 4 5 3 2V„ 

Arsenic. 1% 2 % 2 2 


The old plate glass makers were considerably hampered 
by impure materials, and were forced to make a very fluid 
and alkaline glass. Knapp’s Technology, 1843, contains the 
following analysis of St. Gobain glass and formula used 
there according to Bastenaire : 


St. Gobain. 


Sand..".. 100 

Soda. 35 

Lime. 5 

Cullet. 100 


Decolorer 


Bastenaire. 

Sand. 100 

Soda. go 

Carbonate of Lime. 13 

Cullet.ioo 

Peroxide of Manganese. 1 

Smalt. 05 


It will be seen that the amount of lime is entirely insufli- 
cient in both cases, and that the amount of soda used 


(6 pounds to 100 of sand) is entirely out of proportion. And 
still, one must not expect too much from people who were 










































glassm akers’ hand-book. 


51 


forced to use a different batch as the seasons changed, so 
that in the Encyclopedia articles published as late as 1883* 
we have what might be called a u summer ” and a u winter ” 
batch, because the furnaces were alleged to draw better in 
cold than in warm weather. 

The researches of Faraday have shown that soda is pre¬ 
ferable to potash in plate glass manufacture, as the latter 
attracts noisture and injures the color. Experience has 
shown that soda dries and loses its water of crystalization, 
while potash attracts moisture and becomes liquid. The 
gall resulting from the use of soda, also, consisting mainly 
of sulphate of soda and chloride of sodium, is more vola¬ 
tile than potash gall, and therefore easier gotten rid of in 
the pot. 

Color is one of the prime considerations in plate glass 
manufacture, and hence the use of manganese as a decolor- 
izer should never be resorted to, for reasons previously 
stated. Manganese imparts a violet tint to soda glass, and 
a violet-bluish tinge to glass containing potash. The violet 
is not, however, always sufficient to mask or veil this green 
or yellow tint imparted by the presence of iron in soda 
glass, and as part of the violet tint imparted to the 
metal vanishes in the leer or annealing oven, and thus 
makes color mere accident and guesswork, the amount of 
manganese was reduced, and an addition of smalt or oxide 
of cobalt was added. De Fontenay introduced the use of 
oxide of nickel and abandoned the use of manganese and 
smalt. 

Oxide of nickel is a black powder, and the nickel-oxidule 
(containing more oxygen) of dull green color, have been 
very successfully used as deodorizers. In its native state, 
nickel nearly always is found in combination with cobalt, 
and usually retains traces thereof; hence its effectiveness as 
a substitute for smalt, (which in reality is an enamel or glass 


* Encyclopedia of Chemistry, Lippincott, 1883. 



52 


GLASSM AKERS’ HAND-BOOK. 


colored with cobalt). Nickel-oxidule imparts a bluish tint 
to potash and crystal, and a hyacinth tinge to soda glass. 
Added in excess (from 5 to 7 per cent, of the batch) it yields 
a color resembling the violet imparted by manganese. The 
tints imparted by nickel are constant and do not lose 
strength m passing through the leer or annealing oven, and 
hence are preferable on account of their certain and unvary¬ 
ing reliability. 

For similar reasons the director of the plate glass works 
at St. Grobain* prefers oxide of zinc to manganese as a decol- 
izer. but without giving any explanation for such preference, 
and while the authority is unquestioned, it may be well to 
state that zinc alone has not, during recent American expe¬ 
rience, proven satisfactory. Indeed the statement of 
tfernerf that oxide of zinc was apt to impart a yellow tinge 
was practically confirmed, especially if the glass was not 
rapidly worked after fining. 


Polished plate glass, next to highly pellucid lead Hint, be¬ 
longs to the most perfect products of the glassmaker’s art, 
rivals the diamond in purity and excels it in utility. It ap¬ 
proaches perfection in proportion as it exhibits a high 
polish, uniform thickness, clearness and purity, and conse¬ 
quently there must be a total absence of striae, chords, blis¬ 
ters, seeds ; have permanence of color and be so balanced in 
composition as to endure exposure without liability to 
tinge or discolor. 

From this it is apparent that the purest materials only 
should be used, and that in melting, fining, casting’, polish¬ 
ing and all manipulatory processes the utmost care and 
highest skill must be continually and invariably exercised. 

A careful study of the formulas used in the leading: Euro- 
pean works, and especially the analytical researches and 
minute observations of Weber, as shown in the appended 
tables, will be of interest : 


*Henrivaux, Le Verre et le cristal, 254. 


fGerner, Die Glasfabrikation, 5t>. 



ANALYSIS OF PLATE GLASS. 


GLASSMAKERS’ HAND-BOOK. 


53 


3 

Sh 

a 

© 


O) 

© 

0) 

3 

>-3 


© 

• I-H 

SI 

3 

© 

W 

'd 

c 

3 

© 

3 


O 

bp. 


© 

n. 


© 


© 

A 


-J2 

3 

3 

3 

A 


© 

,3 

m 

3 

H 


W 

o 

£ 

H 

P3 

* 


.2 


© 

A l 


Charleroi, ^ 
Belgium. 


Munster- 
buseh. 
St. Gobain. 


London & 
Manches- 
ter Plate ° 
Glass Co.. 

London 
Plate Glass o> 
Company.. 

British 

Plate Glass jg 
Company.. 


Venetian... 


Bohemian 


Venetian... 


CD 


u) 


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54 


GLASSM AKERS* HAND-BOOK. 


FLINT HOLLOW-WARE. 


The manufacture of flint hollow-ware lias grown to im¬ 
mense proportions during recent years, and in many cases 
has largely displaced green glass. Fruit jars, the use of 
which is growing more extensive each year, especially those 
of large size to displace the shape and color of the contents, 
are now, to a large extent, made of flint, which is preferred 
on account of its greater clearness and transparency. 


Very little need be said in reference to the composition of 
glass used in this branch of manufacture, as it is apparent 
that ware to be used for holding chemicals, medicines, acids, 
etc., should be made so as to offer the greatest resistance to 
the attack of the acids. 


A number of the .best foreign formulas are given, in which 
such changes may be made in the proportions of lime, 
soda and potash, as seem best adapted to glass desired for 
special purposes. 

We append tables showing the composition of different 
glasses of, a careful study of which is commended. 

Attention should no doubt be called to the fact that the 
old recipes contained far less lime than is used to-day, and 
that as a result our glass has a higher polish and greater re¬ 
sistance. In this connection, a study of the recipes previ¬ 
ously given for window glass would be of benefit, as the 
proportions of lime and soda are nearly equal, or often, 
quite so. 


The foreign modern practice is based on the following 
proportions: 


Potash. 

.74-79.5 

.14- 7.6 

.12—12.9 


.79.5—74.8 
.13.0— 7.2 
17.5—18.0 


Silica.. 
Lime... 
Potash 


100—100.0 


Silica 

Lime. 

Soda- 


Soda. 


100.0—100.0 













GLASSMAKERS’ HAND-BOOK 


55 


RECIPES FOR FLINT HOLLOW-WARE. 


i 


FINE WHITE. 


Sand. 100 

Potash, refined. 50 

Lime.’ 20 


Saltpeter.... 
Manganese 
(Juliet. 


2 

02 

100 


2 


BOHEMIAN A. 


Sand. 


Arsenic 

Potash, refined. 


Manganese... 

Lime, hydrate. 


Cullet. 


3 

B. 

Sand. 


Arsenic. 

Potash, refined. 

. 58 

Manganese. 

Lime, hydrate. 

. 12 

Cullet. 

Saltpeter. 

. 8.5 



4 C. 


Sand. 100 

Potash, refined. 50 

Lime. 20 


Saltpeter. 1.6 

Manganese.00.8 

Gullet.100 


COMMON WHITE. 

5 


Sand. 100 

Ground lime. 36 

Soda. 30 


Sand. 100 

Ground lime. 36 

Soda. 33 


Saltpeter. 1 ?/» 

Manganese. 34 

Gullet.100 


Arsenic. 2 

Manganese. 1 

Cullet. 100 


7 


Sand. 100 

Potash.45 

Lime. 16 


Manganese. 34 

Arsenic. 1 

Cullet.100 


8 


Sand. 100 

Lime, hydrate. 40 

Potash. 40 

Salt. 16 


Saltpeter. 8 

Arsenic. 2 

Manganese. 34 

Cullet,.,. 100 “ 






























































56 


GLASSMAKERS* HAND-BOOK. 


9 


Sand. 

. 100 

Arsenic. 



... iy 2 

Soda. 


Manganese. 



... i 

Ground lime. 

. 32 

Cullet. 



... 100 


10 




Sand. 

. 100 

Arsenic. 



... 2 

Soda. 

. 34 

Manganese. 



... iy 2 

Lime. 

. 34 

Cullet. 



... 100 


WITH SALT CAKE. 





1 

2 

3 

4 

• 5 

Sand. 

. 100 

100 

100 

100 

100 

Salt cake. 

. 35 

32 

38 

36 

40 

Lime, ground. 

. 32 

30 

36 

34 

38 

Charcoal. 

. 3 

2% 

4 

5 

6 

Arsenic. 

. 1 

2 


2 

'> 

Manganese. 

V 

2 

1 

1/ 

/2 

1 Vi 

Cullet. 

. 100 

100 

100 

100 

100 


GREEN BOTTLE GLASS. 


The severe tests to which green and amber bottles used 
for export are now put, their submission to pressure, and the 
resistance required in the Pasteurizing process of export beer, 
make the composition of bottle glass of considerable impor¬ 
tance. Actual tests at several large western breweries dur¬ 
ing 1888 proved that bottles made from fresh batch, to which 
only a small quantity of cullet had been added, stood the 
highest tests, the greatest breakage being only two bottles 
per gross. It should be added, also, that the bottles which 
stood the severest tests had been annealed in ovens held at 
a high heat for several hours after the blowing, and very 
carefully and gradually cooled. 

For colors, the cheapest materials are resorted to, such as 
zaffer for blue, manganese for violet, and carbon (usually 
pulverized cannel or anthracite coal) for amber. 

In using salt cake, it must be remembered that all traces 
of salt water must be removed before the coloring oxides are 
added, for reasons elsewhere stated. 

Iron and alumina, always present in impure sand, are not 
























GLASSM AKERS’ HAND-BOOK. 


57 


objectionable in green bottle manufacture; indeed many 
European bottle makers purposely add loam, clay, kaolin, 
etc.; or obtain alumina (and therefore a refractory product) 
from an addition to the batch of native rocks, as described 
on pages 5 and 6, some of which contain as high as 18 per 
cent, of alumina and from 2 to 20 per cent, of iron. 


Foreign recipes are of little use to the American bottle 
maker, as most of those published contain potash and soda 
in such proportions as would lead to bankruptcy, while the 
turf and wood ashes, which so largely enter into their form¬ 
ulas are not so accessible to us. 


Keeping in mind the general rules, that excess of alkali 
reduces resistance; alumina increases it, and in excess, ren¬ 
ders the glass liable to devitrification ; lime adds to polish, 
brilliancy and resistance, and that the larger the pro¬ 
portion of sand melted, the cheaper the product will be; but 
that reduced solvents mean increased heat and fuel, will 
fairly indicate the lines to keep in sight in the practical com¬ 
position of the batch. 


Blast furnace slag has been used at various foreign bottle 
works, at intervals, for more than a century past, but with 
indifferent success, on account of the varying composition of 
such slag. As long as glass sand is as cheap and abundant 
as it is likelv to be in the United States for centuries to 

c/ 

come, there is very little inducement to resort to coarser 
materials, especially as sand is now handled by machinery 
at such a low cost as to make the use of materials otherwise 
handled quite unprofitable. 

That furnace slag may some day be profitably used, how¬ 
ever, in bottle manufacture carried on in tank furnaces, 
where the slag may be introduced in a fluid state will not be 
doubted by any who have observed the wonderful industrial 
developments of recent years. 


ORDINARY GREEN BOTTLE GLASS. 


58 


GLASSMAKERS 5 HAND-BOOK. 


Sulzbach. 


Schueler 


Bechlbuch... 


Montplaisir. 


Vaurrot. 


Schueler 


Schueler 


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Schueler 


ic OiCO I- 

t> eq ® co 
"oq" coic 
oq 


3 


Folleinbray.. 


Trelon 


Schueler 


■_ • »“H CJi co 

Schueler 

g-DOgq 




Clichy. 


Dumas... 


Sevres.. 


Dumas.. 


cc 


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^Liable to devitrify. 
















































































glassmakers’ hand-book. 59 

GREEN BOTTLE GLASS. 



1 

2 

3 

4 

5 

Sand. 


lOt) 

100 

100 

100 

32 

Soda. 


10 

35 

38 

Lime. 


.SK 

32 

30 

100 

Cu 1 let. 

WITH SALT CAKE. 

1(H) 

100 


6 

7 

8 

9 

10 

Sand. 

. 100 

100 

100 

100 

100 

Salt cake. 

. 35 

30 

40 

;i8 

42 

Lime, ground. 


35 

38 

34 

30 

8 

Charcoal. 

AMBER BOTTLE 

4 

GI 

0 

jASS. 

5 


1 

2 

3 

4 

5 


—jr 

— 

— 

— 

— 

Sand. 

. 100 

100 

KM) 

100 

100 

Dime. 

. 30 

38 

34 

35 

37 

38 

Soda. 

. 35 

40 

30 

33' 

l*uveri zed cannelcoal. 8 

0 

0 

11 

14 


6 

7 

8 

9 

10 


— 

— 

— 

— 

— 

Sand. 

. 100 

100 

100 

100 

100 

Salt cake. 

. 32 

34 

30 

38 

40 

Lime. 

. 30 

32 

34 

35 

38 

(’harcoal. 

. 1 

5 

0 % 

0 

8 

Cannel coal. 

. 0 

8 

7 

9 

14 


CRYSTAL GLASS. 


Under this caption lead and lime hint glass properl}'' falls, 
and as American glass manufacture, during recent years, 
has shown a decided tendency toward tine blown ware, lead 
Hint, and the shapely off-hand blown work in which the for¬ 
eign manufacturers formerly met with scarcely any domestic 
competition, a variety of lead glass recipes are given space. 

The very rapid extension of the line cut branch of flint 
glass manufacture in the United States, and the splendid, 
rich, artistic cuttings which challenged the admiration of 
European manufacturers, and carried off" the first prize at 






















60 


GLASSMAKERS* HAND-BOOK. 


the Paris Exposition in 1890* ought to be sufficient encour¬ 
agement to induce Americans to more determined efforts to 
secure industrial conquests in those departments where 
taste, refinement and luxury exact higher tests of merit than 
are required in the pressing of beer mugs or the blowing of 
demijohns. 

It is scarcely necessary to insist upon the importance of 
using the purest materials in fine Hint glass-making, as that 
has been sufficiently stated in other portions of this work. 

The loss of material in crystal glass manufacture, from 
the batch to the finished product, has been theoretically as¬ 
sumed to be 24 per cent., which is a safe figure for all pur¬ 
poses of calculation. 

Gloduret, director of the famous Baccarat works, consid¬ 
ered that to make 100 kilogramsf of finished crystal 
glass, the use of 144 kilograms of batch, consisting of: 


Sand. 72 

Lead. 48 

Potash. 24 


144 

were required. These observations were based on a long and 
varied experience, and he considered that the loss during 
the melt, according to temperature required and the con¬ 
stituents of the batch, amounted to from 13 to 15 per cent., 
or an average of 14; and he assumed that the melting of 
144 kilograms of batch involved a loss of 20 kilograms. 

This loss results from the vanishing of the carbonic acid 
gas of the potash, the development and flight of gases dur¬ 
ing the process of melting ; from the lighter particles being 
carried off during the mixing of the batch, and from broken 
pots. Besides there is often loss from the development of 
glass gall, and a considerable portion of the metal clings to 
the blow pipes and punties, and though this latter portion 


*T. G. Hawkes, Corning, N. Y., was awarded the gold medal. 
*About 2 1-5 pounds. 






GLASSM AKERS* HAND-BOOK. 


61 


is not entirely lost, it is often discolored by oxide of iron, and 
rendered unlit for remelting for the finest grades of crystal, 
without previous cleaning. 

It is best cleaned by subjecting it to a bath of diluted 
sulphuric acid in large boxes lined with sheet lead. The 
cullet must be kept immersed for* twelve hours or more, 
heated to 180 degrees Fahrenheit to dissolve the iron, and 
then be thoroughly washed. 

Clemandot resorted to nickel plating the molds, pipes and 
tools used, and thus prevented iron scales from being mixed 
with the glass. Such practice has not, to our knowledge, 
been adopted in this country, though it lias been used with 
satisfactory results in France for many years. 


RECIPES FOR LEAD CRYSTAL. 


From the foregoing analysis it is clear that as wide a di¬ 
vergence in the composition of lead flint is permissable and 
practical, as demonstrated by the practice of some of the 
foremost European factories, as is the case in any other de¬ 
partment of the glass industry. Attention is especially 
directed to the large amount of silica and the small amount 
of lead contained in lS T os. 1, 2, 3, 4 and 5, of table II on ac¬ 
count of their cheapness and resistance to the influence of 
acids, and hence their adaptability to blown bar goods and 
liollow-ware of the better grades. 


It is to be remembered, however, that such highly silicious 
glass requires a high furnace temperature, and that as the 
amount of lead is reduced the alkaline solvents must be in¬ 
creased. From this change, however, a clearer color results, 
but such glass is of less specific gravity, suffers in brilliancy 


and lustre, and loses the diffractive power, which is the 
tinctive quality of heavy lead flint. 


dis- 



62 


GLASSMAKERS’ HAND-BOOK. 


With open pots, or with covered pots of modern construc¬ 
tion, such ns that patented by Mr. Asa G. Neville, now being 
largely adopted by progressive flint glass manufacturers, 
which is provided with a horizontal removable crown stop¬ 
per or lid, enabling the furnace heat to freely enter the pot 
and facilitate top melting, so that glass can be melted and 
lined in less than twelve hours, very refractory glass can be 
made and no obstacle remains to deter manufacturers from 
making glass of the greatest possible resistance. 


Lead glass is liable to assume a yellow tinge, which be¬ 
comes more decided as the proportion of lead increases, and 
hence must be guarded against by the addition of deodoriz¬ 
ers, such as manganese, oxide of nickel, cobalt, etc. Salt¬ 
peter, if added in quantity, may be substituted for a part of 
the potash, while the addition of a small quantity of borax 
has been found to render flint lime glass suitable for a body 
for casing. 


Sand. 

Pearl ash 

Lead. 

Nitre. 


CHEAP LEAD CRYSTAL. 


. 100 

Borax. 

. 36 

Arsenic. 

. 10 

Manganese... 

5 



8 

-4 


oz. 


RICH LEAD CRYSTAL. 


Sand. 100 

Lead. 48 

Pearl ash. 18 

S< >da..-.. 10 

Nitre. 0 


Arsenic. 234 oz 

Manganese. 1 “ 

Antimony. 34 


LIME CRYSTAL. 


Sand.:. 100 

Soda. 38 

Lime. 10 

Nitre. 0 


Manganese. 3 oz. 

Arsenic.2 “ 

Cobalt. 1 gr. 


The composition of foreign lead flint is shown in the fol- 



























glassmAkers’ hand-book. 


63 


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64 


glassmAkers’ hand-book. 


FINE ENGLISH CRYSTAL. 


i 


Sand... 100 

Lead... 80 

Potash, refined. 10 

2 

Sand. 100 

Lead. 67 

Potash, refined. 35 

3 

Sand. 100 

Lead. 67 

Potash, refined. 28 

Saltpeter. 6 

4 

Sand. 100 

Lead. 12 

Potash. 31 


GERMAN 


Manganese. 0.4 

Saltpeter. 0.5 

Cullet.100 


Arsenic.. 0.3 

Manganese. 0.2 

Cullet.100 


Arsenic. 0.25 

Manganese. 0.2 

Cullet. 100 


Saltpeter. 16 

Manganese. 2 

Cullet. 100 


FLINT. 



Sand ... 
I <ead.... 
Potash 


300 

160 

105 


Lime. 60 

Manganese. 1% 

Cullet.100 “ 


FRENCH CRYSTAL. 


7* 


Sand. 150 

Lead. 00 

Potash.:. 10 

Manganese.1 


Borax. 6 

Arsenic.lo 

Cullet. 100 


FOR OPEN POTS. 


8 


Sand. 100 I Potash. 30 

Lead.. 58 j Cullet.' iqO 


* August Weyer. 























































GLASSMAKERS* HAND-BOOK 


65 


9 


Band. 100 

Lead. 42 

Potash. 33 


Saltpeter. 8 

Manganese. 0.2 

Cullet. 100 


10 


Sand... 

Lead... 

Potash 


100 

30 

45 


Saltpeter. 

Manganese.. 
Cullet.. 


0.25 

100 


11 


Sand. 100 

Lead. 30 

P< >tash. 17 

Saltpeter. 8.5 

1 


Sand. 100 

Lead. 45 

Potash. 35 

13 * 

Sand...’.. 100 

Lead. 12 

Carbonate of lime. 14 

Soda. 46 


Manganese. 0.6 


Salt. 13 

Arsenic. l 

Cullet. 100 


Arsenic. 0.3 

Manganese. 0.2 

Cullet.100 

14* 

Sand. 100 

Lead. 25 

Carbonate of lime. 25 

Soda. 27.5 


*Flamm and Schuer. 


OPTICAL GLASS. 


GUINAUD. 

1 


Sand. 100 

Lead. 100 

Potash, pure. 23 

Borax. 1.75 


Saltpeter. 1.33 

Manganese. 0.45 

Arsenic. 0.45 

Cullet. 22 


BON TEMPS. 


2 3 


Sand. 

Lead. 

Soda, pure. 

Potash, refined. 

Borax. 

Saltpeter. 


CHANCE. 


Sand. 

Lead. 

Potash.... 

Saltpeter 


100 

100 

100 

100 

100 

100 

30 

— 

— 

— 

23 

26 

— 

6.5 

— 

— 

— 

6 . 

•j * 

2t 

3+ 

100 

100 

100 

67 

105 

128 

30 

26.66 

25 

3.33 

4.8 

2 


^Photographic lens. fTelescope. fMicroscope. 

































































66 


GLASSMAKERS 5 HAND-BOOK. 


In regard to the manufacture of optical glass, very little 
is definitely known among American glass makers, and the 
process is one requiring the utmost purity of materials, and 
the most careful manipulation. The process lias been care¬ 
fully guarded abroad, and besides the names of Guinand, 
father and son, Fraunhofer, Utzsclmeider, the Chances, 
Boutemps and Feil, few others have ever successfully pur¬ 
sued its manufacture. Feil, a descendant of Grimaud, man¬ 
ufactured the immense lens for Alvan Clark & Sons, of 
Cambridge, Mass., now at the Lick Observatory, California. 
The lens is 36 inches in diameter, required four days to 
melt, thirty days days to anneal, and so taxed the ingenuity 
of the optician, that though the contract for the glass was 
made in 1880, it was not delivered for more than four years 
later. 

The process of Guinand consisted in stirring the pot con¬ 
tents for fifteen minutes, at stated intervals, during the melt, 
so as to secure a perfectly homogeneous glass, the great 
amount of lead necessarily used having a tendency to settle 
to the bottom and produce stratifications differing in density 
and diffractive power. 

Those desiring to pursue the subject of optical glass fur¬ 
ther than it is possible to treat it in this volume, will find 
valuable pointers in the bibliology of glass in the appendix. 

LIME GLASS. 


The American lime glass for pressed tableware has been 
much admired by European glass makers, so that the fol¬ 
lowing tribute was paid to American pressed ware, made by 
the Central Glass Company, Wheeling, W. Aa., and exhib¬ 
ited at the Paris Exposition in 1878, by Charles Colne,* Sec¬ 
retary to the American Commissioners : 


♦Paris Exposition, 1879, Glass and Glassware, 244, 




GLASSMAKERS’ HAND-BOOK. 


67 


u Many were the inquiries to know how such thin and 
large pieces could be pressed without mold marks and with 
such clearness ol metal. Nothing was found to equal or 
even approach this American pressed ware in any of the 
other departments. The beauty and brilliancy of the metal, 
lime glass, excited the admiration of foreign manufacturers.” 

The following analysis of American pressed glass has been 
published: 


Silica. 

Potash. 

Soda. 

Lime. 

Alumina. 

Baryta. 

Oxide of iron 
Manganese... 


Henrivaux. 

Benrath. 

70.40 

67.1 

8.66 

4.2 

9.13 

10.3 

10.00 

5.1 

0.99 

0.3 


11.9 

0.02 

0.1 

0.50 

trace. 

99.70 

99.9 


I 


Henrivaux* gives the 
American pressed glass: 


following as the composition of 


i 

Sand.:. 100 

Soda. 37 

Nitrate of soda. 8 

Lime. 13 

Arsenic. 0.5 

Manganese. 0.15 


AMERICAN, SOD 


2 3 


Sand. 

. 100 

100 

Soda. 


33 

Potash. 

. 8.5 

33 

Ground lime. 

. 25 

28 

Gullet. 

. 50 

115 


A.—(Present practice.) 


Sand... 

Soda. 

Nitrate of Potash. 

Lime. 10 

Manganese. 0.2 0.1 

Arsenic. X A 


1 

2 

3 

4 

5 

100 

100 

100 

110 

100 

34 

38 

36 

35 

40 

5 

4 

8 

6 

5 

10 

12 

14 

8 

9 


0.3 

0.2 


% 


AMERICAN, POTASH.—(Old practice.) 


Potash 
Lime... 
Nitre... 


1 

2 

3 

4 

5 

— 

— 

— 

— 

— 

100 

100 

100 

100 

100 

30 

32 

36 

34 

32 

16 

14 

8 

13 

12 

K 

34 

% 

1 

i/ 

/2 

1 

% 

2 


X A 


*Le verre et le cristal, 320. 





































GLASSMAKERS’ HAND-BOOK. 


68 


COLORED GLASS. 


Glass is colored by the use of varying proportions of dif¬ 
ferent metallic oxides, prominent among which are cobalt, 
manganese, antimony, iron, chrome, zinc, uranium, copper, 
gold and silver. The intensity and purity of the colors ob¬ 
tained vary with the proportions of the oxides used, and the 
purity of the materials employed in the composition of the 
batch. 

Carbon, in the various forms in which it occurs, colors 
glass from a light straw color to a dark amber, according to 
the amount used. It is generally used for making amber 
bottles, and added to the batch in the form of pulverized an¬ 
thracite coal or coke; birch bark, horn shavings, calcined 
cow or horse hoofs, corn, oats, nut galls, flower of sulphur, or 
any carbon or carbonacious substance, colors amber. 

Phosphate of lime, in the form of bone dust; oxide of tin, 
cryolite, fluor and feldspar, and guano, are used in the man¬ 
ufacture of opal. Cryolite is objectionable because of its 
strong attack on the pots, and hence German glassmakers 
have used Baker’s Island guano, which is free from iron and 
effects the pot to a less extent. 

The analysis* of guano shows its constituents to be 


Moisture. 

Organic matter. 

Soluble salts. 

Sulphate of lime. 

Phosphate of lime. 

Carbonates and silica. 


Jarvis’ Bakers’ 

Island. Island. 

7.50 4.50 

4.00 11.00 

2.50 I 7 00 

5.00 | 7 00 

81.00 76.80 

- 1.50 


100.00 100.00 


Some metallic oxides impart different colors to glass, ac¬ 
cording to the various stages of oxidation. Thus the sub¬ 
oxide of copper colors red ; the protoxide, green. In mak- 


*Prof. John C. Draper, New York. 












GLASSMAKERS’ HAND-BOOK. 


69 


ing copper ruby, therefore, all oxidizing agents must be 
avoided, and powerful reducing agents must be added to the 
batch in order to hold the copper at the state of the sub¬ 
oxide. For this purpose, nitrate of potash, oxide of tin, iron 
scales, etc., are employed. 

Blue glass is produced by oxide of cobalt (or zafter) and 
oxide of copper. 

V ellow, by silver (mostly as a stain in the muffle) chrome, 
uranium and carbon. 

Green, by chrome, protoxide of copper, protoxide of iron, 
or a mixture of blue and yellow. 

Violet, by binoxide of manganese, oxide of gold, or a 
combination of red and blue. 

Ruby, with oxide of gold, or sub-oxide of copper. 

Black glass is usually produced by an excess of manga¬ 
nese, iron, etc. 


GENERAL RULES FOR MAKING COLORS. 


Purity of materials is of the greatest importance in mak¬ 
ing line colors. Such batches as produce line flint, are also 
most suitable for colored glass. Care and judgment must be 
exercised in the proportions of coloring matter added, and 
the oxides should be pure, if line colors are desired ; espe¬ 
cially is this the case in line cobalt blue, gold and copper 
ruby. 

The former practice was to flrst melt a pure flint batch, 
dip out, pulverize, add the coloring oxides, and after inti¬ 
mate admixture, remelt. This method entailed labor; it 
vas circuitous, but certain in its results, if proper propor¬ 
tions of coloring matter had been added, and the batch had 
been correctly compounded. 

The objection to this method was, however, that the colors 
usually lost intensity and grew faint, and hence the modern 
practice of adding the color directly to the batch. 



70 


glassm akers’ hand-book. 


The metallic oxides being of greater specific gravity than 
the other constituents of the batch, these often sink to the 
bottom of the pot, and impart a denser color to it than to 
the rest of the glass. This is especially the case when man¬ 
ganese or other colorizers are added to the fluid glass instead 
of being mixed with the batch. When using salt cake, the 
color must not be added until every trace of salt water has 
been removed, as the carbon, necessarily added to drive ofl* 
the gall, would destroy the violet color imparted by man¬ 
ganese, and prevent other oxides from imparting color to tin* 
glass. 

Colored cullet should only be added to the molten glass, 
and not mixed with a batch containing sulphate solvents. 
An exception to this rule may be made in cullet colored 
with cobalt blue or chrome green, as well as oxides of co¬ 
balt, chrome, tin. uranium and phosphate of lime. 

Oxides of silver, antimony, copper and iron should al¬ 
ways be added to the fluid glass, after the salt water has 
been removed, but it is advisable to avoid the use of sul¬ 
phate of soda when fine colors are desired. 

The pulverized glass, with which the oxides are mixed, 
should be of the same nature as the molten metal to which 
it is added, especially if the glass is to be used for casing or 
flashing, so as to secure an even textured glass throughout 
' the pot. 

When glass is to be cased, the body and casing glass must 
be similar in composition, so that equal contraction and ex¬ 
pansion of the united metal is assured. Gold and copper 
ruby has recently been cased on a lime body glass, to which 
a small quantity of borax had been added.* 

*Dutailly and Lauth, 1890, advise the use of 8.33 per cent, of borax for soften¬ 
ing porcelain glaze. 


GLASSMAKERS 7 HAND-BOOK. 


71 


One advantage of mixing the colors with finely pulverized 
glass, and thus adding them to the molten metal, re¬ 
sults from the fact that the quickly melting glass particles 
melt around and envelop the oxides, prevent their evapora¬ 
tion, hold them from sinking to the bottom, decrease their 
liability to reduction to the metallic state, and thus aid in 
securing a more uniform colored glass. 

Lead glass assumes a finer, fuller, more lustrous color 
than lime glass, hence the amount of coloring matter used 
may be smaller for the former and larger for the latter. 
It is customary to add a small quantity of lead to lime 
batches for colored glass, as that assumes a better color, and 
improves the quality. 

As the coloring oxides largely aid fusion, the usual 
amount of solvents may be reduced one-half the weight of 
the oxides. An addition of finely ground Hint glass of the 
same composition as the colored glass, may be added and 
mixed with the molten metal if the color secured is too in¬ 
tense. 

The proper tones to be secured by the addition of certain 
amounts of oxides, must be ascertained by trial, test and 
experience. As conditions and batch constituents vary, so 
results will differ. Tests in small monkey pots are so cheap 
and so satisfactory in results, that for the costlier colored 
glasses, it is best to first try the color with the sand and 
solvents; especially is this method recommended when the 
purity of the ingredients cannot be ascertained by analysis. 
In these tests it is best to produce the lighter colors first, 
then increasing the amount of coloring matter according to 
the results obtained. A perfect and minute record of these 
tests, the amount, by weight and measure, of all the ingre¬ 
dients used, the degree of heat and length of time required 
in the melting, and all the peculiarities and changes devel¬ 
oped, should always be made and kept for reference and fu¬ 
ture guidance. By such record, experience leads to success. 


GLASSM AKERS’ HAND-BOOK. 


'»> 


BLUE GLASS. 


Cobalt is one of the easiest oxides to handle, and is one 
of the most certain in its results. In soda glass, cobalt has 
a tendency toward violet, and hence when a decided blue is 
desired, a small amount of oxide of iron or oxide of copper 
should be added to strengthen the color. In potash lead 
glass, all the various shades of blue are obtainable. A 
small addition of oxide of nickel or zinc warms and bright¬ 
ens blue. 

Apsley Pellatt* recommended the use of 2 lbs. of oxide of 
cobalt to 600 lbs. of flint batch, for a transparent blue ; and 
6 lbs. of oxide of copper to 600 lbs. of flint batch for an 
azure blue. His recipe for a flint glass was 


Carbonate of potash. 100 lbs. 

Red led or litharge. 200 “ 

Sand. 300 “ 

Saltpeter. 14 to 28 “ 

Oxide of manganese. 4 to 6 ozs. 


KECIPES FOE BLUE GLASS.f 


i 


Sand. 

Potash. 

Borax. 

Lime, slacked 


Sand. 

Potash .... 
Bone ash 
Lime. 


100 

25 

4 

12 


Oxide of cobalt 

Salt. 

A rsenic. 

Cullet, bine. 


2 



100 

45 

32 

13 


Salt. 

Arsenic.. 

Cohalt. 

Blue cullet 


o 



3 


Sand... 
Potash 
Lime... 
Salt. 


100 

34 

12 

2 


Arsenic 
Cobalt.. 
Cullet .. 


'i 


100 


ozs. 


♦Curiosities of Glassmaking. 

-j-The American practice is to substitute an equivalent of soda for potash. 




































HAND-BOOK 


73 


GLASSMAKERS’ 


4 


Sand 

Soda 

Lime. 


Sand. 

Lead. 

Nitrate of soda. 
Arsenic. 




Arsenic 



Za.ffer 



Cnllfvt 

FOR 

CASING. 


5 


100 

18 

10 


y* 


Bicarbonate of soda 

Cobalt. 

Manganese. 

Cullet. 


6 oz. 
100 



FOR SHEET GLASS. 


Sand. 100 

Soda. 35 

Lime. 10 

Bone dust. 10 


Zafler. % 

Arsenic. 1 

Oxide of zinc. 1 


FRENCH.* 


Sand. 100 

Soda. 36 

Chalk (carb. lime). 25 

Lead. 10 


Oxide of cobalt. 0.400 

Oxide of copper... 7 

Saltpeter. 6 

Cullet, flint. 200 


VIOLET GLASS. 


i 


Sand. 100 

Soda. 40 

Lime, slacked. 13 

Saltpeter. 2 

Lead. 2 


VIOLET FOR 


Sand. 100 

Soda. 35 

Lead .. 2 

Lime, slacked. 15 


Arsenic. % 

Violet cullet. 100 

Manganese. 3 

Added to ground glass. 2 

(and mixed with the batch.) 


SHEET GLASS. 


Manganese. 10 

Saltpeter. 2 

Ground glass. 100 


all added to the batch. 


*Henrivaux, Le verre et le cristal, 425, 























































74 


GLASSMAKERS’ HAND-BOOK. 


Sand. 

Soda. 

Carbonate of lime 

Manganese. 

Oxide of iron. 

Saltpeter.. 

Cullet... 


Sand. 

Soda. 

Potash. 

Lead. 

Carbonate of lime 

Cullet. 

Nitrate of Potash. 

Manganese. 

Nitrate of soda. 


VIOLET—BONTEMPS.* 

3 


4 


Blue Violet. Red Violet. 


100 

100 

60 

80 

28 

25 

15 

4 

2 

1 

6 

— 

250 

— 


VIOLET, HENRIVAUX.f 


5 

6 

7 

8 

— 

— 

— 

— 

100 

260 

100 

100 

100 

110 

80 

100 

20 

110 

80 

86 

90 

110 

2 

10 

90 

055 

20 

20 

90 

100 

100 

20 

90 

055 

2 

6 to 8 

22 

4 

10 

5 

12 

4 

10 



GREEN GLASS. 


Oxides of iron, chrome, uranium and copper, as before 
stated, are used for imparting the green color to glass. 

When iron is used, the addition of manganese will impart 
a fine brown shade, such as Avas used by the Romans in the 
manufacture of hollow-ware. Oxide of copper alone will 
not yield a fine green color, and should always be used in 
combination with chrome, the latter of which it is also not 
advisable to nse singly. 

The oxides of iron and copper, with a small addition of 
cobalt, produce a fine, rich green. Copper green is very sen¬ 
sitive to the influence of reducing agents, and even with the 
addition of oxidizing agents, should always be melted in 
covered pots. 

As the oxide of chrome does not readily unite with the 
glass, it imparts a feeble . color. The modern practice dis¬ 
penses almost entirely with chrome, and the yellow and red 
chromate of potash is used instead, but the latter must be 


*The lime in these recipes seems too high, and amount of soda insufficient, 
fllenrivaux, Le verre et le cristal, 426. 





















GLASSM AKERS’ HAND-BOOK. 


75 


used in a very finely pulverized state in order to prevent the 
formation of glass gall. 

Uranium imparts a greenish yellow fluorescence to glass, 
but its fine color is imparted only to Bohemian crystal; that 
is, a highly silicions glass. In lead glass the color shows 
weak and undecided ; the color may be made deeper by the 
addition of small quantities of either iron, chrome or cop¬ 
per oxide. 


RECIPES FOR GREEN GLASS. 


i 


Sand. 100 

Potash. 30 

Lead. 10 


2 

Sand.*.. 100 

Soda. 35 

Lead. 12 


Lime, slacked. 12 

Oxide of copper.:. 4 

Oxide of ii’on. l 


Lime. 12 

Oxide of copper. 3 

Oxide of iron. y 


BOHEMIAN AQUA-MARINE. 

3 


Sand. 100 

Soda. 38 

Lime.:. 12 

Oxide of copper. 8 


Oxide of iron. 4 

Salt. 3 

Arsenic. % 


•bohemian, FLUORESCENT. 

4 


Sand... 
Potash 
Lime.. 


100 

36 

14 


Oxide uranium 

Saltpeter. 

Arsenic. 



% 


FRENCH GREEN. 

5 


Sand. 

Soda. 

Lime. 

Uranium 


100 


36 


13 

3 A 


Oxide of copper 
Oxide of Iron.... 

Manganese. 

Arsenic. 










































7 (> 


GLASSM AKERS 5 HAND-BOOK. 


GREENISH-YELLOW, for Sheet glass. 

6 


Sand. 100 

Salt cake. 38 

Carbonate of lime. 25 


Bone ash. 10 

Yellow (3) or red chromate potash 3 
Plain cullet. 100 


The chromate of potash is dissolved and poured over the sand. 


Sand 

Soda 

Lime 


POMONA GREEN—A. 

7 


100 

35 

22 


Sulphate of copper. 

Arsenic. 

Uranium. 



POMONA GREEN—B. 


• 


8 

Sand. 

. 100 


Ground marble. 

Soda. 

. 38 


Black oxide copper 

Potash. 

. 30 


Uranium. 


32 


GREENISH-YELLOW * 





9 

10 

11 







For open pots. 

Sand. 



100 

100 

260 


Soda.. 



30 

33 

110 


Carbonate of lime. 



23 

20 

55 


Saltpeter. 



7 

7 Nitrate of soda, 05 


Oxide of copper. 



5 

5 

05 


Oxide of iron. 



3 

3 

■ 


Bi-carbonate of potash... 



3 1-5 


1 



CASING 

GREEN. 







12 

13 

14 

15 

Sand. 



. 100 

100 

100 

100 

Potash.:. 



38 

• 36 

35 

34 

Lead. 



58 

40 

26 

18 

Nitrate of soda. 



3 

3 

4 

3 

Oxide of copper. 



8 

6 

5 

4 

Oxide of iron. 



3 

4 

3 

2 

Uranium. 

* 


1 

% 

1 

1 


GREEN. 






16 




Sand. 

. 100 


Lime.... 



£ 

Lead.. 

. 30 


Salt. 



91 / 

Potash. 

. 20 


Chrome aeid 


L /2 

Nitre. 



Arsenic 



i/ 

72 


*Henrivaux, Le verre et le cristal, 435. 














































GLASSM AKERS’ HAND-BOOK. 


77 


YELLOW GLASS. 


A pure, bright yellow is one of the most difficult colors to 
obtain, for the reasons that besides uranium, we have no 
metallic oxide which will regularly and certainly tinge glass 
yellow. Oxide of iron, in combination with manganese, 
tinges from a light to a dark orange, brown or amber. Sil¬ 
ver, in spite of Ebell’s success, has not been generally 
adopted in the production of yellow glass, because it is not 
certain in its results, being easily reduced to the metallic 
state, in which it yields no tinge to silicates. It is generally 
applied to the surface of glassware in the form of a paste, 
and at a comparatively low muffle temperature stains glass 
in all shades of yellow and orange. 

Flower of sulphur, with small additions of reducing agents, 
and all carbonaceous substances impart various shades of 
yellow. Sulphide of antimony is often recommended, but 
outside of its staining power in pastes for the muffle colors, 
it has been found very uncertain its results when added to 
the batch. 

Oats, corn, charcoal, etc., are always reliable, but rarely 
can the same shades of color be produced, because oats or 
corn grown in different fields, or in different parts ^of the 
same field, vary in tlieir constituents according to the chem¬ 
ical composition of the earth in which they flourished, and 
yield varying tints. 

More reliable and uniform is their tinging power is the 
carbon contained in animal horns or hoofs. These are 
placed in a closed iron vessel, and roasted or calcined in a 
sharp fire for about one hour. When cool, they are pulver¬ 
ized, sifted, andjmixed with one-half their weight of potash. 
This mixture is then again calcined until there is an ab¬ 
sence of blue flames. The residue must, after cooling, be 
preserved in air-tight vessels, until used. W hen wanted for 



78 


GLASSMAKERS’ HAND-BOOK 


use, it is mixed with an equal part of pulverized glass, after 
all salt water has been removed. 


RECIPES FOR YELLOW GLASS. 




Sand. 100 

Potash. 40 

Lime. 12 


Arsenic. 

Cullet. 100 

Calcined hoofs > add to melt- f 8 
Pulverized glassJ ed glass \ 5 


OLD GOLD, for Sheet Glass. 

2 


Sand. 100 

Salt cake. 35 

Charcoal. 2 

Carbonate of lime. 20 

Cullet. 100 


Add to melted glass 


Ground glass-. 10 

Manganese.:. 10 

Bone ash.:. 10 

Iron vitriol. 6 


YELLOW, for Sheet Glass. 



3 

4 

5 

Sand. 

. 100 

100 

100 

Soda. 

. 45 

28 

35 

Potash. 


— 

6 

Carbonate of lime. 

. 40 

30-40 

32 

Charcoal. 

. 4 

4 

5 

Arsenic. 

. 1 

Nitrate potash, 1 

1 


Sand. 

Potash. 

Lime. 

Flower of sulphur. 
Arsenic. 


YELLOW, French. 


6 

7 

8 

9 

100 

100 

100 

100 

40 

38 

36 

35 

25 

28 

30 

32 

1 1-5 

P4 

m 

1% 

% 

?2 

i 

V 

/2 


FRENCH GREEN, Bontemps. 

10 


Sand. 

. 100 

Manganese. .. 

Soda. 

. 30 

Oxide of iron 

Ground lime.. 

. 28 

Cullet, flint... 

Nitrate of soda. 

. 6 



15 

2 

250 







































GLASSMAKERS’ HAND-BOOK. 


79 


OPAL AND ALABASTER GLASS. 


The white opaque, or semi-opaque glass, known as opal, 
(or, as the Germans more expressively term it, milk-glass,) 
so long used in the manufacture of shades, smoke bells, and 
vases, has recently largely developed^ and is being continu¬ 
ally made at many factories, being blown and pressed into 
various trinkets, novelties, packing cases, and full lines of 
tableware, finely decorated and burnt in the muffle, have 
given an importance to opal glass, which it has not hereto¬ 
fore possessed. 

It is being made very cheaply at most American factories, 
and European manufacturers have long since almost wholly 
abandoned the use of large quantities of lead in their white 
glass, except for the better grades of ware. Oxide of tin, 
given in most of the old formulas, is now rarely used in or¬ 
dinary opal, on account of its cost. Bone ash, and at a later 
date, cryolite were largely used. 

The modern practice has been in search for a cheaper sub¬ 
stitute, and German manufacturers have of late resorted to 
combinations of fiuor and feldspar, and are making a satis¬ 
factory glass. The white color and opaque quality is im¬ 
parted by phosphate of lime, in whatever manner or form it 
is added to the batch. Hence, attention should be given to 
the action of the colorizer upon the pot. That cryolite is 
very hard on pots, is well known, and it would seem that 
guano is the only practical substitute that does not so fiercely 
attack the pots. Fluor and feldspar attack the pots to even 
a greater extent than cryolite, but they offer an advantage 
from the fact that glass in which they enter can be melted 
at a much lower heat than with cryolite, and consequently 
pots can be made to last longer by being made thicker in the 
sides and bottom. The alumina admixed with opal by the 
attack of the pots, does not seem to be an objection in this 
case, as it leaves no noticeable trace in the finished articles. 



80 


GLASSMAKERS’ HAND-BOOK. 


The amount of lime generally used is very small, and 
opal may be made without, or with but small quantities of 
lead. Smoothness and lustre, and a softer tone are, of 
course, always increased by the addition of lead, but lead- 
less opal, for pressed ware, is generally used, on account of 
its cheapness. The amount of bone ash used to obtain a 
glass that readily turns opaque, is about 20 pounds to 100 of 
sand. In this particular, most of the Encyclopedia articles 
and many of the older published formulas are at fault,. the 
recipe given by Benrath* for instance (6 kg. to 100 of sand) 
has been found entirely insufficient. 

Bone ash glass is brittle and difficult of fusion, and hence 
suitable for decorating in the muffle, as it endures high tem¬ 
peratures without losing shape. All glasses containing a 
high amount of phosphate, however, are liable to oxidize if 
subjected to moisture, and bone ash glass often shows a 
greyish tint after passing through the muffle, because car¬ 
bon flames act as solvents on phosphates. 

When using cryolite, about 14 pounds to 100 of sand .pro¬ 
duces good results. The modern foreign and American 
practice, however, is to use fluor and feldspar instead of cry¬ 
olite, for reasons previously stated. 

On account of fluor and feldspar being largely adulterated 
by additions of lime, which increases the hardness of the 
glass, and enfeebles the color, it is necessary to use large 
quantities, if a decieed opaque glass is desired. They must 
be always used in combination, as separately they yield un- 
. satisfactory results. The proportions used generally abroad* 
are 40 of fluorspar to 100 sand ; and 20 of feldspar to 100 
sand. 

Opal glass is readily colored with metallic oxides, similar 
to crystal, but it modifies the tinging power to some extent, 
and in some colors, imparts a softer and richer tone. Oxide 


*Sprechsaal, 1891, No. 8. 
*Die Glasfabrikation. 




GLASSMAKERS’ HAND-BOOK. 


81 


of copper, which colors crystal a dark blue-green, imparts a 
light Turkish blue to opal. 

Opalescence is imparted to flint glass by the use of less 
phosphate of lime than is necessary to render it opaque 
when first gathered from the pot. The various colors may 
be employed and opalescence imparted by reheating at the 
glory hole. Thus a blue glass, to which phosphate of lime 
has been added, may be rendered entirely opaque, semi¬ 
opaque, or opalescent, according to the amount of lime used, 
or the amount and degree of heat the glass is subjected to 
while being worked. 

It is thus that the various fine color effects of the so-called 
“ Turkish Coral,” “ Eose Blush,” etc., are secured. 

The opal, to which oxide of gold, with reducing agents, 
has been added, can be made to impart its red or ruby tint 
to the white glass by being warmed in. The tint will vary 
in intensity according to the length of time it is exposed to 
the glory hole flame, and the white and red tints may be 
made to flow into each other harshly or softly, according as 
the articles are partially or entirely subjected to the reheat¬ 
ing process. 

By the use of uranium, or chloride of silver, the fine tint 
of Burmese ware is obtained. 

Opal, thus adorned with tints, offers the best and widest 
field for the artistic metal maker and glass worker, and it is 
a direction that is not at present overcrowded, nor likely to 
be, for some time. 

Some very fine color and surface effects are produced by 
acid etching blown lamp bowls, shades, pitchers, etc., thus 
obtaining the so-called satin or bisque finish, and polka dots, 
raised pillar lines and beaded flutes, and the indented or 
projecting portion of patterns and designs are taken advan¬ 
tage of to secure different color and shade effects. 

The following analysis of foreign and American opal will 
give a fair idea of the proportions used : 


GLASSMAKERS’ HAND-BOOK. 


82 


ANALYSIS OF OPAL GLASS. 




European. 


American. 

x . 

ANALYST. 

Peligot. 

Stein. 

Stolba. 

Williams. 

Hagemann 

and 

Joergenson 

Silica. 

.. 80.90 

79.51 

32.00 

63.84 

63.41 

Soda. 

Potash. 

.. 17.60 

16.87 

5.60 

5.66 

10.51 


Cryolite. 

Lime. 

0.70 

2.79 

3.30 

1.85 

15.14 

Oxide of lead... 



— 

— 

- — 

Alumina. 

0.80 


3.20 

7.86 

3.67 

Manganese. 

Oxide of iron.... 

— 


— 

1.50 

{4.40 

Oxide of zinc.... 


— 

— 

6.99 

6..50 

Magnesia. 

Fluor. 


— 

— 

IC‘C 

cn© 

©00 

— 


99.00 

101.17 

99.76 

101.98 

98.16 


RECIPES FOR OPAL. 


Sand. 

Lead. 

Bicarbonate potash 

Feldspar. 

Fluorspar. 

Potash. 

Borax. 

Manganese. 


Sand. 

Soda. 

Lime. 

Oxide of tin 


BRIGHT OPAL. 


1 

2 

3 

— 

— 

— 

100 

100 

100 

38 

35 

20 

10 

8 

8 

35 

38 

40 

25 

20 

22 

19 

16 

18 

1 

1 

1 

% 


99 


A 

100 | 

Fluorspar... 

35 

Feldspar. 

10 

Nitre. 

■5 

Manganese 


FOR SHADES OR PRESSED WARE. 
*5 —A. 


*Nos. 5 and 6 , August Weyer. 


Sand. 100 

Lead. 15 

Soda. 35 

Nitre. 2 


Feldspar. 40 

Fluorspar. 25 


Sand. 100 

Lead. 20 

Cryolite. 6 

Pearl ash. 16 


Feldspar. 38 

Fluorspar. 38 

Borax. 20 

Nitre. i 






































































S3 


GLASSM AKERS’ HAND-BOOK. 


GERMAN CRYOLITE—Ennis. 



7 


Sand. 

. 100 

Nitrate of potash. 

. 2 

Cryolite. 

. 20 

Lead. 

. 2 

Soda. 

. 30 

Zinc. 

. 1 


GERMAN OPAL 

, WITHOUT DEAD. 



8 


9 

Sand. 

. 100 

Sand. 

. 100 

Slacked lime. 

. 16 

Bone ash. 

. 30 

Bone ash. 

. 18 

Potash.. 


Soda. 

. 45 

Soda. 

. 15 

Arsenic. 

. 3 

Saltpeter. 

. 12 



Arsenic. 

. 1.5 


10 


11 

Sand. 

. 100 

Sand.•. 


Lime. 

. 12 

Lime. 

. 13 

Bone ash. 

. 36 

Oxide of zinc. 

. 2 

Potash. 

. 44 

Potash. 

. 38 

Salt 

. 5.5 

Borax. 

. 1 

Arsenic. 

. 0.7 

Salt. 

1 5 

Cullet,. 


Arsenic. 

. 0.25 


FRENCH OPAL, Bontemps. 



12 

— 




. 100 


Borax. 

. 4 

Lead. 

. 120 


Oxide of zinc. 

. 9 

Potash. 

. 30 


Arsenic. 

. 4 

Bone ash. 

. 14 





GERMAN OPAL, FOR shades.* 
13—E-t 


Sand. 

Fluorspar. 
Feldspar.. 
Cryolite ... 


100 

20 

34 

6 


Soda. 

Potash.... 
Saltpeter. 
Lead. 


20 

8 

5 


GERMAN LEAD OPAL.f 


14-C.t 


15-D.f 


Sand. 

Soda. 

Feldspar. 

Kryolite. 

Lead. 

Saltpeter 


100 

10 

13 

14 
6 
3 


Sand. 100 

Fluorspar. 20 

Feldspar. 36 

Soda. 16 

Potash. 12 

Saltpeter. 6 

Lead. 6 


♦Schuer, used at Stettin Glass Works. 

•[Frederick Fischer, Sprechsaal, Nos. 8 and 9,1891. 







































































HAND-BOOK 


84 


GLASSMAKERS’ 


16 


Sand. 100 

Potash. 38 

Soda. 5.5 

Salt. 4.4 

Nitrate of potash. 3.3 


The stopper should be left partly open 
to escape. 


Lead. 11 

Calcined Baker guano.33.3 

Manganese. 0.28 

Borax. 1.70 


r tilling in, to allow the salt fumes 


BRIGHT OPAL LEAD. 

17 


Sand.'.. 

Lead. 

Bi-carbonate of soda. 
Feldspar. 


Sand 

Soda 

Lime 

Nitre 


Sand 

Soda. 

Lime 

Nitre 


100 

80 

10 

8 


Potash. 

Borax. 

Manganese 


LIME OPAL. 

18 


100 

33 

8 

9 


Feldspar 
Arsenic.. 
Bone. 


OPALESCENT. 


19 


100 
42 X 
10 

16-7 


Bone ash. 

Fluorspar.... 

Arsenic. 

Manganese. 


16 

1 

2 


15 

6 

5 


10 

4 

4 


34 


OPALESCENT LEAD. 

20 


Flint batch. 

. 100 

Cryolite. 

2 

Bone. 

. 634 

Oxide of zinc. 

. 2 

Lead. 

. 4 




OPAL LEAD SHADES. 



21 


Sand. 

. 100 

Soda. 

11 

Lead. 

. 30 

Potash. 


Feldspar. 

. 16 

Nitre. 


Flourspar. 

. 16 

Bone. 




Manganese. 

. 2 “ 


COLORED OPAL. 


Marbelized opal lias, during recent years, been made at 
several American factories. Pressed ware lias been oiven 

o 

different colored veins and stratas similar to marble by gath- 






















































GLASSMAKERS’ HAND-BOOK. 


85 


ering opal and amber out of adjoining pots, and dropping 
botli gatherings into the mold. Another method has been 
to gather out of both pots, on the same punty, and some 
very fine effects have thus been obtained. 

Another method sometimes resorted to is to add pulver¬ 
ized glass of a different color, after the pot has been plained, 
and then stir the contents thoroughly, but taking care not 
to allow the glass to get above the working temperature. 

The regular coloring oxides are added to white batches, 
which should be of the same composition and nature, so as 
to shrink and expand equally. 

The following recipes for colored opal are given by 
Tscheuschner* : 


i 


Sand.. 100 

Potash. 20 

Guano (85 per cent.). 25 

Saltpeter.*.. 4 

Lead. 1.5 

Gullet. 110 


2 


Sand. 100 

Soda (pure). 15 

Bone ash. 30 

Saltpeter. 4 

Lead. 1.5 

Gullet. 100 


GOLD AND COPPER RUBY. 


Gold distributes itself uniformly in the molten glass only 
at a very high temperature, while copper readily imparts its 
color at a fair red heat, hence the utmost care must be ex¬ 
ercised during the melt, and the methods whereby gold and 
copper ruby are produced, differ widely. One part of gold, 
as shown by Mueller, imparts a fair ruby tint to 50,000 parts 
of glass, which remains visible up to 100,000 parts, and only 
entirely vanishes at 200,000 parts. 

The finest ruby is obtained in pure lead crystal, and gold 
ruby, when gathered from the pot, shows a light yellow 
tinge, the full color being developed by reheating the glass 
during the manipulatory process, which requires the most 
careful and intelligent workmanship. 

Gold is added to a fine lead crystal batch in the form of 
purple of Cassius prepared as follows : 


*Handbuch der Glasfabrikation. 

















86 


GLASSMAKERS 5 HAND-BOOK. 


*Twenty grammes of gold are dissolved in 100 parts of 
aqua regia, made by the addition of 20 parts of nitric acid 
to 80 parts of commercial hydrochloric acid, the solution 
being evaporated to dryness in a water bath. The residue, 
after being dissolved in water, is filtered and diluted with 7 
or 8 declitres (about 6 cubic inches) of water, and placed in 
contact with tin filings ; a vigorous action ensues, and in a 
few minutes the liquid becomes brown, and deposits a pur¬ 
ple percipitate, which should be washed and dried at a gen¬ 
tle heat, is the purple of Cassius, and is of the following 
composition: 


Stannic acid. 32,746 

Protoxide of tin. 14,618 

Protoxide of gold. 44,772 

Moisture. 7,864 


100,000 

The method of dissolving gold generally pursued by 
American metal makers is simply to place the gold, without 
tin, into equal parts of nitric and muriatic acid, place the 
crucible into a larger dish, surround it with warm sand, and 
put into a warm place. Soon as fully dissolved, the contents 
of the crucible are poured over the sand and thoroughly 
mixed with it. 

The purple of Cassius is poured upon, and intimately 
mixed with the sand, and the whole is added to the other 
constituents of the batch and filled in. 

Kohnsf ruby batch consisted of 


Sand. 


.100 kilograms 

Lead. 


. 125 

Potash. 


. 25 “ 

Saltpeter. 


. 16.6 

Gold. 


. 0.115 


Pohl j used a rich crystal batch, and added 0.0217 grains 
of gold to every 100 kilograms of sand, but at the same time 
recommended the formula used in Bohemian glass works : 


*Pelletier. 
fDingler, 144, 289. 
{Dingier, 175, 384. 













GLASSMAKERS* HAND-BOOK. 87 

Sand. 

Lead. 

Potash ... 

Saltpeter 

Apsley Pellatt* recommended the ricli batch of English 
lead crystal: 


100 kg. 

Antimony. 

. 0f» 

kg. 

190 “ 

Ruby cutlet. 

. 180 

U 

6 “ 

15 “ 

Gold. 


a 


Sand.300 

Red lead. 200 

Carbonate of potash. 100 


Saltpeter. 14 to 28 

Manganese. 4 to 12 oz. 


To 600 pounds of which he added 4 ounces of oxide of gold. 

The recent American practice differs widely from above 
formulas, and vastly cheaper gold ruby is produced. The 
following is selected as one of the best for a medium ruby. 


RECIPES FOR GOLD RUBY. 


i 


Sand. 

.... 100 



Oxide of tin. 


Lead. 

.... 80 



White oxide ammonia. 

.... 13 

Potash. 

.... 32 



Red oxide iron. 

2 “ 

Saltpeter. 

.... 4 



Manganese. 

.... i3K “ 

Regulus antimony. 

.... 1% 


5 

Gold. 

.... IK “ 

Sand. 

. 102 



White of antimony. 


Soda. 

. 102 



Manganese. 

.... 3 “ 

Nitre. 

. 42 



Gold. 


Potash. 

. 9 





Sand. 

... 100 



Oxide of tin. 

. 13 oz. 

Potash... 

... 32 



Red oxide of iron. 

9 “ 

Lead. 

.... 80 



Manganese. 

. 12 “ 

Nitre. 

... 4 



Powdered slate. 

. K 

Black oxide antimony. 

... iy 4 



Gold. 

. IK 



4 

4 



Sand. 

150 lbs. 



Manganese. 

. 2 tbs. 

Lead. 

100 “ 



Saltpeter. 

. 20 “ 

Slate (pulverized and sifted). 

12 “ 



Potash. 

. 75 “ 

Regulus antimony. 

4 “ 






One grain of gold to every 60 lbs. of batch. Dissolve 
gold in equal parts nitric and muriatic acid. By placing 
crucibles in hot sand the dissolution of gold is facilitated. 
Pour acid and gold over batch, mix well, and fill in. When 
plain, gather and work. Color is developed in a hot leer. 


^Curiosities of Glassmaking. 





















































88 


GLASSMAKERS’ HAND-BOOK. 


COPPEE EITBY. 


Copper ruby is more difficult to make than gold. The 
copper requires less heat than gold, as the fusing point of 
gold is 2016 degress Fahrenheit, while copper fuses at 1996 
degrees. These figures refer to wrought metal, and a less 
heat is sufficient to distribute the oxides in the pot when 
they are added to the batch in a finely reduced state. The 
oxide of copper must be accompanied by strong reducing 
agents, to hold it to a lower state of oxidation, as previously 
explained, as then only does it stain glass red. If the re¬ 
duction is carried too far, the spangled effect of aventurin, 
instead of ruby, will be the result. 

The pots in which copper ruby is to be made should be 
partially surrounded with perforated jack brick, so as to 
enable air jets to play upon the sides, and thus hold the tem¬ 
perature under control. The small pots and furnaces used 
abroad are of the greatest advantage to the glassmaker, and 
facilitate the production of uniform tints. In this country, 
the Neville pot offers such advantages in the manufacture of 
flint, and especially the sensitive colored glasses, that they 
must speedily come into general use. 

When proper amounts of reducing agents have been em¬ 
ployed, and the furnace temperature well graduated, the 
color should be of a fine, bright, rich, transparent ruby, 
without a tendency to dark or brown shades. 

If the reduction has been carried beyond the proper point, 
the glass will appear opaque, and assume a tendency toward 
a coral or sealing-wax red. Examined under the micro¬ 
scope (magnified 200 times) it will show fine metallic crvs- 
tals, which, at still further reduction will show the spangles 
of aventurin to the naked eye. Thus it very often happens 
that when trying to make copper ruby, aventurin is the re¬ 
sult, and vice versa. 



89 


GLASSMAKERS’ HAND-BOOK. 

In regard to copper ruby pot metal, the remarks of Prof. 
Barff* in reference to the ruby stain seem to be especially 
applicable: 

Black oxides of copper, when mixed with glass and melted 
in a glass-pot, makes the glass green; suboxide of copper, 
which contains less oxygen than the black oxide, when 
treated in the same way, makes it red. Now, if it can be 
reduced to the lower oxide of copper, while the black oxide 
of copper on the surface of the glass is heated, it will then 
color the glass red. The best way of reducing the black ox¬ 
ide, is to connect the muffle with a gas-supply pipe, and 
allow coal gas to pass during the whole time that the heat¬ 
ing process goes on. The action of the gas, which contains 
hydrogen and carbon, is to take away oxygen from the black 
oxide of copper, when it is at a high temperature; and, as 
soon as sufficient is taken away by the hydrogen to reduce 
the black oxide to the state of suboxide, it stains the glass 
red. 

RECIPES FOR COPPER RUBY. 


FOR CASING 



. 100 

Gullet. 

. 100 

Carbonate of soda. 

. 28 

Oxide of copper. 

. 4 

Lime, slacked. 

. 24 

Oxide of iron. 

. 4 

Lead .. 

. 8 

Nitrate of potash. 



2 




. 100 

Oxide of tin. 



.... 38 

Oxide of iron. 

. 4 


66 

Nitrate of potash. 

. 10 

Oxide of copper. 

. 7 




3 



. . 100 

Oxide of copper. 

. 6 


Oxide of tin. 

. 5 

T ood 

... 40 

Iron scales. 

. 4 



Nitrate of potash. 

. 6 

♦Article: Glass and Silicates in British Manufacturing Industries, 

page 122 . 





























90 


HAND-BOOK. 


GLASSMAKERS’ 


4 


Sand. 

. 100 

Oxide of copper. 

. 4 

Potash. 


Oxide of iron 


. 2 

Lime. 

. 18 

Manganese. 


. 1 

Lead. 

. 4 

Nitrate of potash. 

. 10 


5 



Sand. 

. 21 

Copper. 


. 8 oz. 

Lead. 

. 10 

Tin. 


. zy 9 “ 

Pearl ash. 

. 7 

Iron. 


. 



Charcoal. 


. 




6 

7 

Batch. 



100 

100 

Potash. 



8 

30 

Lime . 




12 

Soda. 



25 

25 

Sulphate of copper. 



7.5 

7 

Sulphate of sodium. 



10.5 

Borax, 1% 

Borax. 



0.5 

— 




8 

9 

Sand. 



100 

100 

Potash. 



25 

as 

Soda. 



10 

8 

Sulphate of copper. 



7 

4 

Sulphate sodium. 



1K 

24 

Borax. 




4 


10 




FINE AMETHIST. 



Sand. 

. 150 

Nitre. 



Lead. 

. 70 

Manganese.... 


. 7 

Potash. 

. 40 

Arsenic. 


. 10 oz 

Lime. 

. 10 

Salt. 


2 

Soda.. 

. 8 





BLACK GLASS. 


Black glass, though made only to a limited extent in this 
country, is very extensively manufactured in the old world, 
where it is put to a thousand uses, for buttons, heads of shawl 
and hairpins, breastpins, ring sets, beads; and blown into 
sheets, is largely used for sign painting. 

For fine work, where pin and needle heads are to be 
melted at the blow-pipe, a lead crystal is used as a base; for 
ordinary purposes, it is advisable to use a fairly compounded 
lime glass. The color for the better quality is obtained by 












































GI - A SSM A K ERS ’ 11A NT)-HOOK. 


1)1 


excessive additions of the oxides of iron, manganese, copper, 
cobalt and nickel; common black glass is made from fur¬ 
nace slag, iron ore, lava, and rocks containing a large 
amount of oxide of iron. Our common glass sand is so 
cheap, however, that there is hardly any inducement to look 
for substitutes, and black is one of the easiest, cheapest and 
most permanent colors with which the glassmaker has to 
deal. 

Light grey glass is now mostly used for spectacles, and 
blue glass is being displaced. From the liability of glass 
colored with manganese, to undergo change, it has been 
almost entirely abandoned abroad for spectacle glass, and 
oxide of nickel is used instead. 

The formula recommended by Bontemps for grey spec¬ 
tacle glass will be found in No. 1. 


RECIPES FOR BLACK GLASS. 


Sand. 100 

Lead. ,50 

Potash. 28 

Soda. 10 


Manganese. 

Oxide of iron. 

Oxide of copper 


4 

8 

i 


BLACK, FOR PRESSED OR BLOWN WARE, 



2 

3 

4 

5 

6 

Sand. 

. 100 

100 

100 

100 

100 

Potash. 

. 36 

— 

15 

— 


Soda. 

— 

35 

24 

38 

36 

Lime. 

. 13 

14 

18 

12 

10 

Oxide of copper. 

. 10 

8 

4 

6 

2 

Oxide of iron. 

. 10 

G 

4 

8 

2 

Manganese. 

. 10 

G 

5 

4 

4 

Zaffer. 

. 10 

3 

2 

3 

1 


BLACK, for Blow-pipe Work. 


Sand. 100 Zaffer.. 

Lead. 84 Manganese. 

Soda. 35 Oxide of iron. 

Saltpeter. 6 i Oxide of copper. 

Flint Cutlet may be added to reduce the intensity of the color. 


G 

G 

2 

3 




























92 


GLASSM AKERS* HAND-BOOK. 


COMMON BLACK. 

8 


Green cullet. 

Soda. 

Lime. 

Arsenic. 


100 

38 

18 

2 


/ 


Manganese. 

Oxide of iron.. 

Pulverized coke.. 


8 

<> 

4 


9 


Flint, batch. 100 

Manganese. 634 

Oxide of iron. 


ART GLASS 


Properly, art glass embraces all those fine color combina¬ 
tions, tints, shades and effects in which Venice of old ex¬ 
celled, and when from her famed Murano the furnace lights 
died out, Bohemia took up, adding the fine-lined engraving. 
England enobled it with her heavy Hint, France and Austria 
breathed shapeliness, beauty and flowing-lined grace, and 
here and there in the United States a Hobbs, Leighton, 
Northwood, Weyer, or Locke, has brought forth tints that 
rivalled the beauty of the sea shell. 

Some color combinations have recently been placed upon 
the market about which the least said the better. In order 
to accomplish anything worthy of placing ourselves in line 
with the fine color effects of European makers, our metal 
makers and managers must pay more attention to the prin¬ 
ciples of harmony. As a pointer, we invite attention to the 
following principles of harmony, founded on the patient and 
erudite researches of M. Chevreul, a careful study of which 
will enable metal makers to so blend and combine their 
colors that they shall be in accordance with the rules of art. 














GLASSM AKERS’ HAND-BOOK. 


93 


ANALYSIS OF LIGHT AND COLOR 


THE SOURCE OF COLOR. 

As light is the source of color, it is necessary to commence 
with an examination of its composition, as the laws of con¬ 
trast of colors are entirely dependent upon it. 

When a ray of sunshine, or white light, as it is termed, 
passes through a glass prism, it is decomposed, or separated, 
and if the image formed, called the prismatic spectrum, is 
received upon a white screen, placed at a suitable distance 
from the prism, it will be found to consist of various colors, 
arranged in a certain order, like those of the rainbow. 

These colors are six in number : three of which are simple; 
and three which are compound, resulting from the mixture 
of the simple colors in pairs. 

Blue, red, and yellow are simple, or primary colors. 

Green, violet, and orange are compound, or secondary 
colors. 

The mixture of blue with red produces violet. 

The mixture of blue with yellow produces green. 

The mixture of red with yellow produces orange. 

These compound colors vary in hue according to the pro¬ 
portions of the simple colors of which they are formed : 

thus, by increasing the quantity of blue in the mixture of 
blue and red, we produce purple, indigo, etc. The same 

effect takes place with greens. 

The primary colors are simple and pure, they cannot, like 
the secondaries, be produced by the mixture of other colors. 

It is evident that the color of the primaries cannot vary 
as color (or in hue), but only in intensity, at least so long as 
they are kept pure, but the hues of the secondaries may vary 
infinitely, according as one or the other predominates. 



94 


GLASSMAKERS’ HAND-BOOK. 

COMBREMEN TA BY COLORS. 


As white light is composed of three colors, blue, red and 
yellow, the color that is missing from the compound is 
termed the Complementary Color ; thus— 

Blue is the complementary of orange (red and yellow). 

Red is the complementary of green (blue and yellow). 

Yellow is the complementary of violet (blue and red). 

By this it will be seen that the complementary of a pri¬ 
mary color is the secondary composed of the other two pri¬ 
maries, and vice versa ; thus : 

Orange (red and yellow) is complementary to blue. 

Green (blue and yellow) is complemetary to red. 

Violet (red and blue) is complementary to yellow. 

If the blue is tinged with red, its complementary, or¬ 
ange, will be yellower. 

If the blue is tinged with yellow, its complementary, 
orange, will be redder. 

If the red is tinged with blue, its complementary, green, 
will be yellower. 

If the red is tinged with yellow, its complementary, 
green, will be bluer. 

If the yellow is tinged with red, its complementary, vio¬ 
let, will be bluer. 

If the yellow is tinged with blue, its complementary, 
violet will be redder. 


CIRCUMSTANCES WHICH MODIFY A COLOR. 


A given color, red, for instance, may experience many 
modifications, so as to appear very different from what it 
really is, according to the circumstances under which it is 
viewed. 




GLASSMAKERS’ HAND-BOOK. 


95 


It may be modified in its color: 

1. By being placed in contact with blue, the red appears 
yellower. 

2. By being placed in contact with yellow, it appears 

bluer. 

3. By being placed in contact with green, it appears 
purer and brighter. 

4. By being placed in contact with black, it appears dul¬ 
ler. 

5. By being placed in contact with white, it appears 
lighter and brighter. 

6. By being placed in contact with grey, it appears 
brighter. 

Thus the same red may appear many different reds ac¬ 
cording to the circumstances under which it is viewed. 

It may also be modified in its intensity, or tone. 

Thus, if a dark color be placed beside a different, but 
lighter color, the dark color appears deeper, and the light 
color appears lighter. This is the result of contrast of tone. 

A color is also greatly modified by gloss, as is shown by 
the plumage of birds, the wings of butterflies, and by cer¬ 
tain flowers. 

The colors of objects are also greatly modified by the form 
of the object, which may produce varieties of light and 
shade, and thus exhibit many tones of the same color. 

Both the tone and the hue of a colored object are modi¬ 
fied by the quality of light by which it is illumined, whether 
it be direct sunlight, diffused daylight, or diffused reflected 

light. 


96 


GLASSM AKERS* HAND-BOOK. 


MODIFICATIONS PRODUCED IN A COLOR BY 
BEING PLACED IN CONTACT WITH 
ANOTHER COLOR, 


If we look at two stripes of the same color, but of differ¬ 
ent tones, or at two stripes of different colors taken at the 
same tone, and placed side by side, if the stripes be not too 
wide, the eye perceives certain modifications, affecting both 
the quality and the intensity of the colors, and they will ap¬ 
pear very differently from what they do when viewed sepa- 
rately. 

First, the tone of each stripe will appear changed, the 
light tone will appear lighter, and the deep tone deeper, 
commencing at the line of contact, where it will be greatest, 
and gradually diminishing as it recedes from it: this is a 
contrast of tone. 

Secondly, the color of the different stripes will appear 
changed, each appearing as differently as possible from the 
other : this is contrast of color. 

The contiguous colors are modified in hue, as if the com¬ 
plementary of the neighboring color was added to each. 

These modifications, taken together, constitute simultane¬ 
ous contrast of color: which may be expressed in the fol¬ 
lowing terms : 

Whenever the eye sees at the same time two contiguous 
colors, they will appear as disimilar as possible, both 
in their hue and in their tone. 

Thus, if the stripes be blue and yellow, the complement¬ 
ary of blue, which is orange, is added to the yellow, making 
it appear redder, and more brilliant; while violet, the com¬ 
plementary of* yellow, is added to the blue, making the lat¬ 
ter apppar indigo ; the color added to each being red, the 
primary absent from the view of the contiguous stripes. If 
the stripes be secondary colors, as orange and green, the 
complementary of orange, blue, is added to the green, mak- 



GLASSMAKERS* HAND-BOOK. 


97 


ing it appear bluer, and red, the complementary of green, is 
added to the orange, making it appear redder ; or, what is 
the same thing, yellow, the absent complementary color, is 
subtracted from each contiguous color ; thus— 


The complementary of orange is blue. 

The complementary of green is red. 

The absent complementary is yellow. 

This yellow subtracted from orange makes it appear red, 
and yellow subtracted from green makes it appear blue, for 
Orange is composed of red and yellow, and 
Green is composed of blue and yellow. 

When we look for a few moments at a given color, the 
eye spontaneously calls up the complementary to that color, 
which, being added to the color first looked at, makes it ap¬ 
pear duller, or tarnished. The effect is the same as if a 
quantity of grey was added to the color looked at, because 
the complementary color added to the original color pro¬ 
duces black. 

This calling up of the secondary color by the eye consti¬ 
tutes the phenomenon of successive contrast. 

And the addition of this color so called up to the original 
color constitutes mixed contrast. 


It will be seen that the result of viewing a single color is 
different from that produced by viewing two different colors, 
because the influence of the juxtaposed color is absent; 
there is no complementary color to add to the color looked 
at. 


The height of tone exercises much influence upon the 
modification ; for if, after looking at orange, we look at deep 
blue, this latter will appear green rather than violet, a result 
the reverse of that presented by light blue. 

Whenever there is a great difference between two contig¬ 
uous colors, the difference is rendered more apparent by 


brinsdna the same color successively in contact 

o O 


with differ¬ 


ent colors belonging to the same group. 


98 


GLASSMAKERS’ HAND-BOOK. 

Example. —If we place orange beside scarlet red, nor¬ 
mal red, or crimson red, the red becomes bluer, or 
purple, and the orange becomes yellower by losing its 
red. 

Tf we plaee normal red in contact with orange red, 
the first will appear purple, and the second yellower : 
but if we put the normal red in contact with purple 
red, the latter will appear bluer, and the other yel¬ 
lower. 

Thus, simple or primary oolors, when in contact, 
pass insensibly into secondary or compound colors; 
for the same red becomes purple or orange, according 
as it is placed in contact with orange red or with pur¬ 
ple red ; the same yellow appears orange or green, ac¬ 
cording as it is placed in contact with orange yellow 
or with greenish yellow ; so also blue appears green 
or violet, according as it is placed in contact with 
greenish blue or with violet blue. 

When we examine any two patterns of the same color, 
such as blue or red, if they are not identical when compared 
together, we must consider that the difference is exaggerated 
by contrast. Thus, if one is greenish blue, it will make the 
other appear less green or more indigo, or even more violet 
than it really is ; and by a reciprocal influence, the other 
will appear greener than when viewed alone. It is the same 
with the reds ; if one is more orange than the other, the lat¬ 
ter will appear more purple, and the former more orange, 
than it really is. 

As soon as we know the complementary of one color in 
contact with another, it is easv to determine what kind of 
modification the second will receive from the first, as this 
modification is the result of the mixture of the complement¬ 
ary with the contiguous color. 

The process is easy when the contiguous colors are both 
primaries, and it is not more difficult when they are both 


I 


GLASSMAKERS* HAND-BOOK. <)<) 

secondaries ; for we have only to consider that the comple¬ 
mentary called up being much less intense than the color to 
which it is added, we obtain the result by subtracting from 
the latter secondary a portion of that primary which, with 
the complementary, forms white light; thus— 

Orange, added as a complementary to green, neutral¬ 
izes a portion of the green, and consequently makes it 
appear yellower ; and the green, added to a portion of 
red m the orange, neutralizes it, and makes the oranae 
appear yellower. 


VITRIFICATION OF EARTHS BY 


METALLIC 


OXIDES. 


All the metallic oxides that are not reduced by mere heat 
to the reguline state or volatized, when subjected to fire, run 
into a true glass which is always more or less tinged, and 
often possesses such a body of color as to be quite opaque. 
The heat at which the oxides vitrify varies extremely, in no 
instance is it less than a red heat, and in many a very in¬ 
tense white heat is required. All the vitrified oxides are 
powerful fluxes for the earths, though less in proportion than 
the alkalies. They give their own color to the vitrified 
mixture and increase its density. 

The vitrifying power of several of the oxides over the 
different earths has been examined in a series of valuable 
experiments by Aehard, of which the following table will 
furnish an abstract. It may be premised that the silica was 
prepared from liquids or flints, and apparently very pure, 
the calcareous earth was carbonate of lime precipitated from 
the muriate by a carbonated alkali; the magnesia from Epsom 
salt in the same way, and the alumina from alum. The 
oxide of copper was the green carbonated oxide prepared 
from the nitrate by carbonate of potash ; the oxides of iron, 



100 


GLASSMAKERS’ HAND-BOOK. 


lead, and zinc, the same; the oxides of tin, bismuth, and 
antimony were also prepared by nitric acid, and therefore 
in the highest state of oxidation. 

All these mixtures were exposed in earthen crucibles to 
the heat of a porcelain furnace during the whole time re¬ 
quired to bake the porcelain. 


Mixture. Ratio. Result. Color and Texture. 

Sand. 11 . 1 black and polished—hard, 

Oxide of iron. 1j hCOIia - / giving sparks with steel. 

O xi'de of iron. 1 j not fase( * j black and friable. 

Sand. 11 scoria run through the cruci-1 black and hard—sci n ti 1- 

Oxide of iron. 2 / ble J lant. 

SeifTO^r:::: i} notfuse<1 . } 

Oxide of copper.... 4} no ^ fused j 

Oxide of lead. 1 } a solid mass but not fused j white and hard. 

Oxide of load. 2/ tied j- yellow—not scmtillant. 

Oxide of lead..""" 3 } P erfect » lass j green—not scintillant. 

Oxide of tin..... ’.. ’.. 1 j a coherent mass j-grey—easily friable. 

Sand. 1 1 vitrify 1 greenish yellow—not scin- 

Oxideoftin. 2 j vit d J tillant. 

Oxide of bismuth.. 1} remained in powder } 

Sand. 1 1 nnvwt o-ines ) deep yellow—not scintil- 

Oxide of bismuth.. 4 / P ertect glass j iant. 

Oxide antimony..! \ } * lass } colorless-scintillant. 

Oxide antimony... 1 ] no ^ ine ^ed j grey and friable. 

Oxide of zinc.'.'.:.’:l} remained in powder j 

Oxide of zinc. 2 j the crucible j-white haid. 

Oxide of zinc......’... 3 } Perfectly fused j grey—scintillant. 

Oxide of iron.. 1 j a melted porous mass j black—scintillant. 

Lime...... 11 melted, polished in thefrac-1 . . 

Oxide of copper 1/ ture, part of copper reduced/ iea scintUi ant. 

Lime.. 31 1 

Oxide of copper. 1 j melted, but porous > the same. 

Lime. 41 part only melted, the rest! 

Oxide of copper. 1/ pulverulent j-grey. 

oxweofieid:::::::: }}*>»» } grce £j* t h yellow " BCintn - 












































» 


C4LAS8MAKERV hand-book. 


101 


Mixtur e. Ratio. Result. Color and Texture. 

Lime... . 2) glass run through the cruel-1 

Oxide of lead. 1 / ble | yellow—scintillant. 

Lime. 3 ) , 

Oxide of lead. 1/ remained m powder 

Lime. 1 ) . . . . i 

Oxide of tin. 1 j' semi-vitrified j yellow—scintillant. 

oxweoftin::::::::: yeuow-»«intii- 

Lime.3 (melted only where touching) 

Oxide of tin. 1/ the crucible /grey. 

Lime..4) , ) greenish yellow—s e inti 1- 

Oxide of tm. i/gutss j j ant 

Lime. l) .. . „ ) 

Oxide of bismuth. 2 } vltnfor m mass j green. 

(txi^e antimVmy 1 [gtass penetrating the crucible | yellow—scintillant. 

Lime. 2) , . , ) 

Oxide antimony... 1 / remained in powder 

Oxide"antimony... 4 j "* ass penetrating the crucible j deep yellow—scintillant. 

Lime. 4) a semi-transparent polished) voll ., w <a _, 1 . tl .n 0 „ 1 . 

Oxide antimony... 1 ) mass | grey yellow scintillant. 

Oxide zinc 1} " lass \ deep yellow—scintillant. 

Oxide of iron. 1 j onl -V P artl y fused } 

Oxide of iron. 3 j a me ^ d porous mass j- black—scintillant. 

Oxide of copper.... 1 / on ^ partially fused j 

Alumina. 1) ., ) 

Oxide of copper.... 4/* 16 saIne f 

Oxide’of lead:::::::: 1 } remained in powder } 

Alumina. 1 ( th ) 

Oxide of lead. 3 j me same / 

Oxide 1 of lead.......! 4 } S lass } dee P ycllow-scintillant. 

Alumina. lla melted porous mass, not) . 

Oxide of tin. 2j polished in the tracture scinuiiant. 

OxkiTor bismuth.'. 2} Paf 'al'y ttoed } 

oxide of antimony 4 } ° nly partlaIly fusc<i } 

oS of zinc::::::: 4 } remalne d to powder } 

Oxid^of iron.......! 3 } half fused » but not cohering j 

Oxi g de C of copper.::. 3} a P° rous half ' fused mass }grey-scintillant. 

Magnesia. 1). not fused l 

Oxide of lead. 3 / ol rusea j 

Magnesia. l)a porous melted mass, part) 

Oxide of lead. 4j of the oxide reduced j 

Oxweofantimony 3 } b «* lnnln * to fusc J grey-scintillant. 

























































102 


GLASSMAKERS’ HAND-BOOK. 


The above experiments (selected from a much larger num¬ 
ber) are mostly confirmed by Kirwan. Notwithstanding 
various anomalies, owing principally to the action of the 
materials on the crucible itself, they are interesting in show¬ 
ing in some degree the comparative fusibility of metallic ox¬ 
ides, and in confirming former observations on the fusi¬ 
bility of the respective earths. Among the metallic oxides 
that of antimony seems to act the most powerfully as a flux, 
and next to this, lead. In almost all the above examples 
where fusion at all took place, the mass became hard enough 
to strike fire with steel, a degree of hardness which is not 
very common with the alkaline glasses. 

VITRIFICATION OF EARTHS WITH SALINE 

BODIES. 

We shall here also give in a tabular form a few of the nu¬ 
merous experiments of Achard (A) and of Morveau (M) 
permising that in each the mixture of the earths and salts 
was contained in a clay crucible which was always acted on 
more or less during the vitrification, and where the salt was 
in excess was often entirely corroded, a circumstance which 
throws some confusion on the results. In the experiments 
of Achard the crucibles were exposed for three hours to the 
heat of a very strong wind furnace ; in those of Morveau 
the crucibes were kept for two hours at a heat of from 22 to 
2b Wedgwood, and therefore probably much lower than the 
former. 

Mixture. Ratio. Resuet. 


A. Sand. 

Carbonate of potash. 

M. Sand. 

Carbonate of soda (dry) 

A. Sand. 

Carbonate of potash. 

A. Sand. 

Carbonate of potash. 

M. Sand. 

Borax (calcined). 

A. Sand. 

Boraeic acid...:. 

A. Sand. 

Boracic acid. 


11 a yellow glass, not hard enough to give 
1 ) sparks with steel. 

1) a colorless transparent glass, but deli- 
2 / quescent from the excess of alkali. 

Q ) 

! -a yellow glass, not scintillant. 

4 ) a vitriform mass, yellow, hard, and scin- 

1 j tillant. 

11 a beautiful transparent glass, not at all 

2 j soluble in water. 

I I a white porcelain mass, scarcely scintil- 

II lant. 

2 1 a hard transparent glass, scintillant. 























GLASSMAKERS 5 HAND-BOOK. 


103 


Mixture. 

A. Sand. 

Boracic acid. 

A. Sand. 

Calcined borax. 

A. Sand. 

Calcined borax. 

A. Sand. 

Sulphate of soda. 


Ratio. _ Resuet. 

.... 4 \ a white opaque melted porous mass,scin- 
.... if tillant. 

31 

1 f a transparent glass, hard and scintillant. 

.... 4) a mass resembling agate, but perfectly 
.... 2 J fused and scintillant. 

2) 

I -a green scintillant glass. 


A. Sand.,. 

Nitre. 

A. Sand. 

Common salt. 

M. Sand... 

Phosphate of soda and ammonia 

M. Lime. 

Carbonate of soda. 


31 

j ' a soft green transparent glass. 

2 | scoria,the crucible entirely destroyed. 

11a white opaque, puffy, vitreous mass, 
2 / deliquescent and reddening litmus. 

1 la white spongy opaque mass, crumbling 

2 j between the fingers. 


A. Chalk. 

Carbonate of potash. 

A. Chalk. 

Carbonate of potash 

A. Chalk.. 

Carbonate of potash 

M. Lime. 

Borax. 

A. Chalk.. 

Borax. 


21 partly fused, the rest pulverulent, the 

1 j crucible strongly corroded. 

11 a well-fused, polished, black scintillant 

2 j glass. 

1 j remained a white powder. 

1) a tine transparent yellowish glass, the 

2 f crucible strongly corroded. 

4 » a well-fused, black, scintillant polished 
1 j mass. 


A. Chalk. 

Borax. 

A. Chalk. 

Boracic acid. 

A. Chalk. 

Sulphate of soda 

A. Chalk. 

S u 1 plia t e of soda. 

A. Chalk. 

Nitrate of soda... 

A. Chalk. 

Common salt. 


j j- a yellow scintillant glass. 

J a yellow glass, run through the crucible. 

j-a hard yellow scintillant glass. 

I | a hard brown scoria, the crucible totally 

4 f destroyed. 

II a ha rd yellow glass. 

1 la yellow scintillant glass, the crucible 
lj entirely destroyed. 


M. Lime. 

Phosphate of soda and ammonia 

M. Alumina. 

Carbonate of soda. 


j a white opaque crumbly mass. 

1) a grey opaque ill-fused frit, not adhering 
2f to the crucible and deliquescent. 


A. Alumina. 44 

Carbonate of soda and potash in >remained unmelted and uncohermg. 
all proportions from. 1 to 12 j 

A. Alumina..... 1 I partially melted, but soft and friable. 

Carbonate of potash. 4 ) 


M. Alumina. 1 )„ a q ne transparent clear green glass. 

Borax. 2 j 

A. Alumina. 1 I. remained pulverulent. 

Borax. 1 j 

\ Alumina 1 I part unfused and remained pulverulent, 

Boracic acid. 4/ the rest partially melted. 

M. Alumina....... 1 l a green frit easily friable. 

Phosphate ot soda and ammonia 2 j ° ___ 

N. B.—Most of the other combinations of alumina with the several neutral 
salts, even in large proportions of the latter, remained unfused, except where 
the crucible was entirely corroded and melted down along with its contents. 






























































104 


GLASSM AKERS 5 HAND-BOOK. 


Mixture. Ratio. Result. 

M. Magnesia . i} a white opaque incohering mass. 

Carbonate of soda. 2 j 

. r . ,)a semi-transparent somewhat milky 

M. Magnesia. * l glass of a gelatinous appearance, but 

Borax. 2 j very hard and brilliant on the surface 

M. Magnesia. 11a white mass a little agglutinated but 

Phosphate of soda and ammonia 2 j not adhering to the crucible. 

M. Barytes (pure). 1) a ve.iy hard semi-vitrified mass, of a 

Carbonate of soda. 2 j clear green. 

M It., vuinc 1 ) a beautiful transparent glass with a faint 

iV1 ‘ I},,!.,I-. o - yellow tinge, strongly adhering to 

h5o,ax . “'j the crucible. 

M ‘ pfiofttate of ainmonia 2 } » remarkably fine transparent glass. 


ACTION OF VITRIFYING MATERIALS ON. THE 
CRUCIBLES THAT CONTAIN THEM. ; 


In estimating the proper action of vitriliable substances 
on each other, the nature of the vessels that contain them 
should always lie taken into account, as a want of this pre¬ 
caution may readily lead to the most erroneous conclusions. 
The celebrated Pott seems to have been the first who very 
distinctly pointed out this circumstance, and several curious 
experiments have been made by Gerhard, which deserve 
further notice. 

This able chemist exposed a variety of natural minerals 
to a very high heat for an hour, under circumstances as ex¬ 
actly similar as possible, except with this difference, that 
one specimen of each mineral was inclosed in a crucible of 
(day, another in one of chalk, and a third in one of char¬ 
coal, and the difference in the result was particularly noticed. 
A few of these may also be given in a tabular form. 

The minuteness of these observations are such as make 
them especially valuable to those engaged in the finer grades 
of flint, and optical glass, and for photographic and spec¬ 
tacle lenses, where the least impurity and aberration of color 
injures the metal, and where it is of the utmost importance 
to trace effects to their causes. 




















glassm akers’ hand-book. 


105 


SUBSTANCE 

USED. 

RESUET IN CEAY 
CRUCIBEE (A). 

RESUET IN THE CHAEK 
CRUCIBEE (B). 

IN CHARCOAE 
CRUCIBEE (C). 

Common flint. ■ 

opaque and milk- 
white, but withont 
fusion 

** 

opaque and white, but' 
with beginning fusion 
where in contact with 
the crucible 

-as in A. 


Marble.{ ru ^^ nto a green) 

ftvnsnm f run into a radiated) 

ij-ypsum.| green glass | 

(melted and ran) 

Fluorspar.- through the cruci- - 

( hie j 

Porcelain clav f com pact white and) 
force lam ciay j no signs of f usion J 

Ditto, another f a compact mass par-) 
kind. \ tially melted j 

(a black glass cov-) 

Reddle.-< ered with a crust > 

( of reduced i.ton j 

{ no fusion, but the) 
color changed to > 
brown J 


no change | no change. 

no change j no change. 

melted down with the) scarcely altered, 
crucible to a tough > except sight fu¬ 
sing J sion at the edges. 

run into a hard blue - ) . . 

clear glass jasinA. 

a perfectly black glass jas in A. 

a semi-transparent ap-P a JjJSYa i nTn e 
"legreen glass f 

completely fused in the) 
parts touching the >as in A. 
crucible ) 


Muscovy talc.. 

Spanish chalk 
Basalt. 


( ) the whole crucible was 

a black glass with | 

-j interspersed grains J- 

| of iron | 


ts) 

penetrated with a) 
scoria so as not to fall [-as in A. 
to powder on expos-1 
ure to air J 


only hardened 


) a. 

J 


grey semi-transparent) • 
glass } as m 


A. 


f““o^ SO Wlth l a w! Ui n many 
l iron.j a crust 01 iron j grains of iron. 


In all the above experiments, except in that of the Mus¬ 
covy talc, the chalk crucible was completely calcined to lime 
on exposure to air. The difference therefore between the 
action of the clay crucible and that of chalk, both respects 
the different fusibility of common clay and lime, and what¬ 
ever action the carbonic acid that is escaping from the chalk 
may have upon the enclosed materials. 

Similar and very valuable experiments have been repeated 
by Professor Klaproth in crucibles of clay and charcoal, in 
which these differences are very striking. 

Some of the most illustrative of them are the following: 

WHITE ALABASTER. 

(In the charcoal crucible.) Was rendered moderately 
hard, its color was white passing to straw yellow, with a 






















106 


GLASSMAKERS’ HAND-BOOK. 

fine grained earthy fracture, it adhered to the tongue and 
euiitted an odor like a sulphuret; loss of weight, .56. 

(In the clay crucible.) Gave a black brown glass, very 
shining, little transparent on the edges. 

BASALT. 

(In charcoal crucible.) Fused into a compact brown glass, 
transparent in splinters. Externally partly glazed brown, 
partly covered with a ferruginous crust, and large grains of 
iron. 

(In clay crucible.) Gave a solid black glass covered with 
a brown steel grey veined iron crust. 

BOHEMIAN GARNET. 

(In charcoal crucible.) Gave a grey turbid glass full of 
grains of iron. 

(In clay crucible.) Melted into an opaque almost com¬ 
pact scoria, whose color internally changed by stripes from 
brown to green, very finely corroded. 

HORNBLENDE. 

(In charcoal crucible. A hardened, ill-shaped mass with 
grains of iron. Color light grey, fracture uneven, without 
any trace of vitrification. 

(In clay crucible.) Melted into a dense black-brown 
glass, transparent in the fragments : of a smooth surface and 
a flat conchoidal, glossy fracture. 

CARRARA MARBLE. 

(In charcoal crucible.) Was converted into quick-lime. 

(In clay crucible.) Changed into a dense, clear, hard, pale, 
grass-green glass. 

STRONTIA NITE. 

(In charcoal crucible.) Form unaltered; hardened by 
ignition, rendered dull and very caustic ; loss of weight , 0.31. 

(In clay crucible.) A clear bright grass-green glass. 

WITHERITE. 

(In charcoal crucible.) In repeated experiments the char¬ 
coal crucible was found for the most part consumed. Hence 


GLASSMAKERS’ HAND-BOOK. 


107 


the witherite always entered into imperfect fusion with the 
contiguous part of the crucible, which served as a case to 
the charcoal crucible. 

(In clay crucible.) A green, somewhat muddy, frothy 
glass. 


In speaking therefore of the fusibility of all verifiable 
mixtures, the nature of the vessel that contains them should 
always be taken into account, so that, as Klaproth has well 
observed, the usual division of earths and stones into fusible 
and infusible requires correction from this circumstance. 
Thus when strontianite, marble, and in general all species 
of calcareous earth vitrify in the melting vessels, it is en¬ 
tirely owing to the mutual action of the earth and the clay 
Crucible, since they remain unfused in the charcoal crucible. 

The charcoal also it will be observed in these experiments 
has often opportunity of acting in the usual manner of car¬ 
bonaceous mixtures, as in reducing gypsum to a sulphuret 
of lime, and assisting in the calcination of the carbonates of 
lime, strontian and barytes. 


It also has another action which tends to diminish the 
natural fusibility of stones, and this is the reduction of the 
iron contained in them, which, when an oxide, is itself a 
powerful flux. Hence it is that several stones naturally fu¬ 
sible will not vitrify in a charcoal crucible, of which the 
basalt is an example, as this mineral readily melts per se into 
a black glass ; but when in contact with charcoal, the oxide 
of iron is reduced, and globules of metallic iron sweat out 
as it were, or separate by a kind of eliquation, and the basalt 
then appears, if examined by a lens, almost wholly corroded 
but not changed into a scoria or at all vitrified, except by a 
much more intense and long continued heat. This separa¬ 
tion of the iron by charcoal, as Klaproth further remarks, 
takes place even in those stones which hardly appear to sof¬ 
ten in the fire, and yet the globules of iron exude on the sur¬ 
face. 


108 


GLASSMAKERS’ HAND-BOOK. 


The color of earths when perfectly vitrified and not in 
contact with charcoal, is for the most part of a cold sea- 
green passing into emerald green, and sometimes with a 
tinge of brown, where the glass is at all transparent. This 
is also observable in the common bottle glass, and those vi- 
trescent mixtures where unpurified ashes are employed in¬ 
stead of pure alkali. This color appears to be entirely ow¬ 
ing to the presence of iron, which is always contained more 
or less in common clays and in vegetable ashes, as was de¬ 
monstrated by Sclieele, who obtained a satisfactory indication 
of this metal in the analysis of a green ordinary glass. 

Some experiments of Mr. Mushet on the affinities of the 
different earths for carbon at excessively high heats, show in 
a satisfactary manner the gradual change produced on this 
natural green color by the admixture of charcoal in various 
doses. A few of these we shall relate. 

1. Some lime from calcined chalk was heated without 
addition in a crucible of Stourbridge clay, at a heat of 166 
Wedgwood, and fused into a perfect dense glass, quite trans¬ 
parent and of a green approaching to emerald. 

2. Fifty grains of the same lime were mixed with 1 grain 
of lampblack (a very pure carbon) and fused as before. The 
result was a lead-blue, greenish color. The charcoal had 
disappeared, but no globules of reduced iron could be ob¬ 
served. 

3. Fifty grains of lime with 2] of charcoal gave a. dense 
glass, of a dark lead blue. Part of the charcoal remained 
uncombined with the glass, and a number of globules of iron 
were revived. 

1. A crystal of double refracting spar was melted per se¬ 
ns before into a very perfect glass of a rich amber color. 

2. Twenty grains of the same spar mixed with 1 grain of 
charcoal fused into a deep, fiery, amber-colored glass. All 
the charcoal had disappeared. 


GLASSMAKERS’ HAND-BOOK. 


I 


109 


3. Twenty grains of the same spar with 11 grain of char¬ 
coal melted into a glass of a cloudy, milky lead color. A 
minute portion of the charcoal remained and many globules 
of iron were seen on the surface. 

From these experiments it appears that any admixture of 
carbon below what is necessary to reduce the iron only al¬ 
ters the shade of color, giving in some instances an amber 
red, in others a dull lead blue, which is possibly in part ow¬ 
ing to an actual combination of the charcoal with the glass, 
but more probably to be chiefly ascribed to a partial deoxi¬ 
dation of the oxide of iron contained in the earth ; as nu¬ 
merous experiments, which have already been noticed, show 
that the coloring power of all the metallic oxides is materi¬ 
ally affected by the degree of oxidation. But when the 
charcoal is sufficient entirely to deoxidize the iron the 
transparency of the glass is destroyed, and the color is,a 
muddy blue, like that of a partially reduced vitrified iron 
ore. 

It is still doubtful whether carbon has any real affinity for 
any of the earths in a vitrified state, that is, whether the 
carbon is properly dissolved in the earthy glasses or only 
diffused through them in a state of very minute division. 
In all Mr. Mushet’s experiments with the other earths and 
carbon, where the latter was in any excess above what might 
be supposed necessary merely to deoxidize the iron, the 
resulting glass received pretty uniformly a more or less deep 
tinge of muddy lead or slate blue, which appears much more 
like a mere diffusion of the carbon through the glass than a 
perfect solution in it. 

ANNEALING GLASS. 


Most of our American glass is imperfectly annealed. Ex¬ 
amined under the microscope, flint tableware, especially 
pitchers of large size and ware handled by hand, shows 



no 


glassmakers’ hand-book. 


fissures, strains, crizzles and cracks, which sooner or later let 
go and cause breakage. 

The handles are generally put on the body glass when it 
is too cold, and the pitchers or other vessels are so much 
thinner on the sides than the base of the handle, that no 
subsequent heating or cooling process in any leer or any 
temperature can possibly cure what must, under improper 
manipulation or workmanship, be called a structural defect 
in most flint ware, the handles of which have been put on 
by hand. This evil is often increased when the glass for the 
handles is gathered out of a different pot, for the sake of 
convenience, or for color effect, and when, especially, the 
glass for the handles is of a nature or composition different 
from the glass used in the body of the vessel to which the 
handle is to be attached. 

So much nonsense has been written about the Prince Ru¬ 
pert drops, that in this work we have heretofore eschewed 
mentioning those royal, convenient, and interesting “ devil’s 
tears,” about which learned Encyclopediasts have expatiated 
to voluminously, illustrated so extensively and explained 
with so much scientific verbosity. 

The researches of De Luynes have shown that the form¬ 
erly accepted theory of molecular strains as exhibited in the 
Prince Rupert drops is erroneous, and that such “ drops ” 
do not invariably explode when the lower point is broken 
off. He showed, rather, that there are layers, stratas or 
laminations in all glasses, varying in molecular structure 
and arrangement of particles according to the thickness of 
the glass, and the method of annealing employed. 

This becomes clearly apparent from an examination of the 
following tabular statement, submitted by Schott, and pub¬ 
lished in the Verhandlungen des Vereins fur die Beforder- 
ung des Gewerbefleisses. 


Ill 


GLASSMAKERS’ HAND-BOOK. 

TABLE SHOWING RESISTANCE AND NATURE OF 
FRACTIONAL STRUCTURE OF GLASS UNDER 
DIFFERENT METHODS OF ANNEALING * * 


Method of Annealing. 


3 

o 


<T> 

v 


o 

-! ft# 

VI 

*d o 22. 

‘O'? yi 

3 3 S’ 

3 S & 


■3 » 

<T> ® 


Natuke of Fkactiire. 


Cooled in annealing oven. 


Cooled in the open air.- 

Rapidly chilled to 100° from / 
(A.) low red heat.j 

(B.) Medium red heat.j 

(C.) Bright red heat. 

Rapidly cooled to 120° from 
(A.) low red heat. 

(B.) Medium red head. 


(C.) Bright red heat. 


Rapidly chilled to 140° from/ 
(A.) low red heat.I 

(B.) Medium red heat. 

(C.) Bright red heat. 

Rapidly chilled to 180° from j 
(A.) low red heat.1 

(B.) Medium red heat. 

(C.) Bright red heat. 


1 

2 

3 

1 

2 

3 

4 

1 

2 

1 

2 

1 

1 

2 

3 

4 

1 

2 

1 

2 

3 

1 

2 

1 

1 

1 

1 

1 


5.87 i 

5.68 > Clear surface breakage. 
4.69) 


12.661 

9.52 

9.9 

7.22 


At fracture a 
piece of up¬ 
per surface' 
thrown off of 


80 mm. 
150 mm. 
80 mm. 
20 mm. 


1- in length 

J 


32*47 } Numerous surface cracks. 


17.98) Numerous splinters flew off' dur- 
20.51 >- ing cooling process. 

54.22 j Audible detonation at splintering. 


21.58 

96.24 

23.65 

12.03 


Exceptionally strong splintering. 


31.97) 

32.83 J 

32.49) 

29.68 > Faultless tubes. 

36.03J 

30.13 ( Splintering during process. 
11.82 j Faulty tubes. 

41.6 


36.33 


23.85 |- 

16.66 

38.72 


Considering that the resistance of cast iron is only equal 
to 29 kg. to the square millimeter, the preceding tests show 
that the resistance of glass, resulting from strains and en¬ 
forced chilling, may be higher, on the average, than that of 


cast iron. 

This structural lamination results from the rush of mole¬ 
cules to adjust themselves immediately at the inception of 
the cooling process. The outer and inner surfaces of the 


*Schott, Verhandlungen des Vereins fur Berfoerderung des Gewerbefleisses, 
79 273 

/Millimeter—0.03937, or nearly 1-25 inch. 



































112 GLASSMAKERS* HAND-BOOK. 

glass, exposed to the atmosphere, chill first and set them¬ 
selves, while yet the particles between the so exposed sur¬ 
faces are in a fluid, or partially fluid, condition. Compressed 
between these casements, opposed by the rigidity of the en¬ 
veloping laminations, the inner molecules compress upon 
themselves, and the resulting strain, stress and crush cause 
the structural fissures which cause the explosion of the 
blown proof, the Bolognes flask, the Rupert drop, or a poorly 
annealed glass article at any time, when touched by a suffi¬ 
cient vibrating force at the point where the strain is greatest. 

Thus some of our large pressed pitchers will readily drop 
their bottoms, if an ordinary marble is dropped in from a 
height of ten or twelve inches. The bottoms are pressed 
thicker than the sides. The lip and part of the body is 
warmed in, and then the handle is put on. The sides chill, 
and are cooled and set before the particles in the bottom 
have had time to arrange themselves. The vessel is placed 
in the leer, but no subsequent annealing can possibly rem¬ 
edy such structural defects. 

In the manufacture of bottles, a similar structural defect 
exists, which is greater, as the glass is unevenly distributed 
at the bottom, sides and neck. A very hot annealing oven 
somewhat reduces these strains, but never removes them. 

The remedy for all these defects must be sought in the 
quicker handling of the finished ware. 

Any improvement or appliance which will facilitate the 
prompt conveyance of finished articles to the leer or oven, 
will obviate these structural strains, and the requirements of 
the bottling trade, far more exacting than the dealers, buyers 
and sellers of tableware, are such that those manufacturers 
who earliest adapt their plants to modern trade demands, and 
leave the old foot-worn paths of conservatism pursued for 
centuries, will reap increased trade and profit. The demand 
is for better annealed goods. 

To anneal properly, ware ought to be placed in the leer or 


GLASSMAKERS* HAND-BOOK. 


113 


oven hot; as hot as possible, without destroying the form 
and shape of the articles. 

From what has been already said, it would seem unneces¬ 
sary to say much about annealing lamp chimneys. They 
are thin, and when evenly blown and made of lead glass, 
(and lime glass is not fit to put into chimneys) there is little 
tendency to molecular strain. The slower they are with¬ 
drawn from the leer, however, the better, and in this respect 
the modern leer is an abomination, especially in large fac¬ 
tories where the leer capacity is often overtaxed. Large, 
heavy iron leer boxes, which retain and slowly give out 
their heat to the enclosed ware, have been used with the 
best results, and are to be highly commended. 

The time has, we think, about passed when chimneys are 
made to break rather than last, and the increasing trade en¬ 
joyed by the best makers of lead glass chimneys, notably 
George Macbeth & Co., Pittsburgh, Pa., whose lead flint 
chimneys are exported to Belgium, France and Germany, 
should be an incentive and induce manufacturers to make 
chimneys not merely to sell, but to so behave when they are 
sold, as not to disgrace “their maker and creator.” 

ANALYSIS OF GLASS.— Bontemps Method. 


As it is frequently important for a manufacturer to ascer¬ 
tain the ingredients making up certain kinds of glass which 
he may want to reproduce, the following is given by Bon¬ 
temps as one of the most reliable methods he has found dur¬ 
ing his long experience as a glassmaker : 

The glass must first be broken to pieces, then reduced to 
powder in a steel mortar. Sieve and take away all metallic 
particles by means of a magnet; further pulverization may 
be continued in an agate mortar. 

Take two grams of the glass powder, put it into a plati¬ 
num capsule. Take a leaden vase of about 25 centimeters 



114 


0 

GLASSMAKERS’ HAND-BOOK. 

diameter and 6 deep, having a cover of same metal; spread 
upon the bottom of this vase some pulverized fluoride of 
calcium; add a sufficient quantity of concentrated sulphu¬ 
ric acid to form a thick batter, which must not rise above 
two centimeters* above the bottom. Place upon this bottom 
a leaden ring 5 centimeters wide by 0.025 high. Upon this 
ring place the capsule containing the glass, and add a little 
water to it; then cover the vase. Warm slightly over a sand 
bath ; the vapor arising will condense into the water con¬ 
tained in the capsule, will attack the vitreous matter, and 
produce fluoride of silicium, which will volatilize. Stir the 
matter now and then with a spatula. At the expiration of 
twelve hours, when the matter has been completely reduced, 
pour sulphuric acid into the capsule to transform the fluor¬ 
ides of the bases into sulphates. Evaporate to dryness; 
expel the excess of sulphuric acid by means of heat; then 
treat the dry mass with water, ammonia, and carbonate of 
ammonia; boil, filter, and wash in warm, water. The re¬ 
siduum may contain sulphate of baryta, carbonates of lead, 
bismuth, lime, some alumina, and oxide of iron. The fil¬ 
tered liquor contains the alkalies in the state of sulphates, 
traces of magnesia, and an excess of carbonate of ammonia, 
mixed with the sulphate. 

To separate the substances contained in the residuum, 
treat with dilute hydrochloric acid, which will dissolve all 
with the exception of the sulphate of baryta, which may be 
gathered upon a filter; wash it and burn the filter in a pla¬ 
tinum crucible. 116,6 of sulphate corresponds to 76.6 of 
baryta. The weight of baryta is fo be deducted from that 
of the sulphate of baryta, according to this proportion. 

Pass sulphureted hydrogen through the acid filtered liq¬ 
uor ; this will precipitate the sulphurets of lead and bis¬ 
muth ; then filter to separate them from the liquor. Burn 
the filter in a porcelain crucible, sprinkle the matter with 


♦Centimeter, equal to£9j368 inch. 



115 


GLASSM AKERS’ HAND-BOOK. 

nitric acid, containing a little sulphuric acid, to transform 
the lead into sulphate of lead, which is insoluble. The 
greater part of the free sulphuric acid is now driven off. 
The residuum is treated with water and filtered. Sulphate 
of bismuth is thus separated from the sulphate of lead. Ac¬ 
cording to the weight of the sulphate of lead the quantity 
of oxide is calculated, 151.5 of sulphate of lead being equal 
to 111.5 of oxide of lead. Treat the acid sulphate of bis¬ 
muth with carbonate of ammonia; the carbonate of bis¬ 
muth thus obtained is calcined, and thereby produces oxide 
of bismuth, the weight of which is to be determined. The 
liquor, containing an excess of sulpliureted hydrogen, is 
boiled in order to expel it; add a few drops of nitric acid to 
oxidize the iron if there should be any; then add caustic 
ammonia sligliffy in excess; this will produce alumina and 
protoxide of iron together. Ascertain the weight of this 
precipitate after having calcined it; then dissolve it in con¬ 
centrated hydrochloric acid and add an excess of caustic 
potash. The iron is precipitated while the alumina is redis¬ 
solved. Filter, wash with boiling water, and ascertain the 
weight of the oxide of iron ; in subtracting it from the 
weight of the alumina and oxide of iron liereabove, the dif¬ 
ference is the weight of the alumina. The liquor now con¬ 
tains only lime, with traces of magnesia, which may be 
negleeted. Add to it oxalate of ammonia, which will pro¬ 
duce insoluble oxalate of lime; filter, wash, and calcine at a 
high heat cadable of transforming the oxalate into a carbon¬ 
ate, then into caustic lime, the weight of which is ascer¬ 
tained. 

If zinc is contained in the glass, it will be found in the 
liquor containing the alkalies, and before dosing these alka¬ 
lies the zinc should be precipitated by hydrosulphate of am¬ 
monia. The sulphuret of zinc is received on a filter, washed 
with water containing a few drops of hydrosulphate of am¬ 
monia ; dry and burn the filter in a platinum capsule. Sul- 




116 


GLASSM AKERS 7 HAND-BOOK. 


phate of zinc is then obtained by a careful roasting. Weigh 
the zinc. 

To dose the alkalies, take the filtered liquor which con¬ 
tains them; evaporate to dryness; heat the residuum, in 
order to get rid of the ammonia salts, which are volatilized. 
Treat with water and hydrate of baryta, which is added in 
sufficient quantity to precipitate all the sulphuric acid of the 
sulphates, and a little magnesia, if there should be any. 
Filter, to separate the caustic potash and soda which are in 
solution with the excess of baryta; then add carbonate of 
ammonia. Carbonate of potash and soda and carbonate of 

t 

baryta are produced ; filter, to separate the latter. Evapo¬ 
rate to dryness, and calcine to expel the excess of carbonate 
of ammonia. Finally, saturate the residuum with a few 
drops of hydrochloric acid. Evaporate to dryness, calcine 
and weigh the chloride of potassium and of sodium. The 
chloride of potassium must now be separated from the chlo¬ 
ride of sodium. 

Dissolve the two chlorides in a small quantity of water, 
and pour a concentrated dissolution of perchloride of plat¬ 
inum until the liquor turns a deep yellow. Evaporate the 
liquor to dryness, and operating with alcohol the double 
chloride of platinum and sodium is dissolved. There re¬ 
mains the double chloride of potassium and platinum, which 
is gathered upon a filter. Wash it with alcohol and weigh 
it after desiccation. 244 of the double salt are equivalent to 
74.5 of chloride of potassium. Knowing the weight of chlo¬ 
ride of potassium and that of chloride of potassium and so¬ 
dium united, the weight of the chloride of sodium is de¬ 
ducted. We now calculate the weight of the soda and 
potash contained in the glass, knowing that 74.5 of chloride 
of potassium is equivalent to 47 of potash, and that 58.5 of 
chloride of sodium is equivalent to 31 of soda. 

All the elements of the glass but silica have now been as¬ 
certained. It may be obtained by difference, but it is always 



GALSSMAKERS* HAND-BOOK. 


117 


best to get it by a direct dosing. To obtain it, mix 2 grams 
of glass with abont 6 grams of dry and pure carbonate of 
soda ; melt in a platinum crucible in a muffle fire. Put the 
crucible containing the well-melted matter in a large porce¬ 
lain capsule, with water and hydrochloric acid (use nitric 
acid when the glass contains lead) ; the matter is dissolved 
with effervescence. When the dissolution is complete, take 
away the platinum crucible, wash it several times, then 
evaporate all over a sand bath ; heat pretty high towards 
the end. Pour over the evaporated matter hot water acid¬ 
ulated with one of the two acids; leave it to digest and di¬ 
lute with water. All the metallic oxides are dissolved, and 
silica only remains as an insoluble residuum. Gather it 
upon a filter, calcine it after a good washing, and weigh. 

To find sulphate of soda, take the liquor from which silica 
has been removed, and which must contain all the sulphate 
of soda which is to be found in the glass ; add an excess of 
chloride of barium ; boil for a long while, and let it settle 
for about twelve hours. Receive upon a filter the sulphate 
of baryta produced, and from its weight deduct the quan¬ 
tity of sulphuric acid, and consequently, the equivalent 
quantity of sulphate of soda. 

To obtain boracic acid, heat the pulverized matter with 
carbonate of soda to redness ; boil the reddened mass with 
water. Filter, and by means of carbonate of ammonia the 
small quantity of alumina and silicic acid which has been 
dissolved by the alkaline liquor is precipitated. Evaporate 
to dryness, treat with sulphuric acid, and digest the re¬ 
siduum with alcohol, which dissolves the boracic acid. Satu¬ 
rate the solution with ammonia, redden the residuum which 
contains the boracic acid, and then ascertain the weight. 

To obtain magnesia, use carbonate of soda. Magnesia 
still remains in solution after having precipitated the lime 
by means of oxalate of ammonia, since it cannot be precipi- 
tated by any of the reagents used until now. Concentrate 


118 


GLASSMAKERS’ HAND-BOOK. 

the filtered liquor by evaporation ; add phosphate of soda 
to it. After twenty-four hours all the magnesia is precipi¬ 
tated in the form of ammonia-phosphate of magnesia, which 
is gathered upon a filter and washed with ammoniated 
water. 112 parts of this precipitate, calcined, correspond to 
40 of magnesia. 

The analysis of glass is a very delicate operation, and it 
is always well to ascertain the right dosing by repeating the 
operations several times. 

POTASH.—A New Test for Potash 

M. L. de Koninck finds that if a 10 per cent, solution of 
sodium nitrate is mixed with cobalt chloride and acetic acid, 
the liquid forms a reagent for the detection of potash much 
more sensitive than platinum chloride. An immediate yel¬ 
low precipitate is obtained in a solution containing one part 
potash chloride in 100 parts of water. It is still perceptible 
if diluted to 1.1000, but in the proportion 1.2000 a precipi¬ 
tate is no longer obtained. Ammonia gives a similar but 
much less sensitive reaction ; magnesium, barium, strontium, 
iron, aluminum, and zinc salts are not precipitated by this 
reagent. 

Estimation of Potash. 

Whenever possible, potash should lie estimated in the form 
of platinum salt. The results are exact and unvarying, and 
the} 7 are attended with the great advantage that, owing to 
the high atomic weight of platinum, any errors of manipu¬ 
lation, unless beyond the limits of probability, affect but 
slightly , the percentage result of potash. To obtain trust¬ 
worthy results several precautions have to be attended to ; 
these have been fully described by Messrs. F. T. Teselie 
maclier and J. Denham Smith, and the following process, 
which have been verified on many occasions, is condensed 
from their description.* 

It is assumed that the salt under examination is a sample 


♦Chemical News, xvii., 221. 



GLASSM AKERS’ HAND-BOOK. 


119 


of commercial potash chloride, or that the alkalies exist in 
such a condition that, by the addition of hydrochloric acid 
in excess, they will be converted into chlorides. Take 500 
grains ot the salt, previously carefully ground and mixed, 
and dissolve it in water, filtering if requisite, and washing 
the insoluble portion till solution and washings measure 
5000 grains. Mix this solution by pouring from one glass to 
another, and take 500 measured grains of the liquid (meas¬ 
ured accurately, always at one level of the eye and one level 
of liquid and line of measurement), dilute these 500 grains 
till they measure 5000 liquid grains and mix; 1000 meas¬ 
ured grains of this solution contain 10 grains of the original 
salt. 

Now, to 1000 measured grains of this solution, add excess, 
say 50 grains, of hydrochloric acid, if the alkalies are not 
present as chlorides, and pour into a shallow porcelain dish, 
making, with the rinsings of the measure, etc., some 1500 
grains of solution. Heat the dish and contents nearly to 
ebullition, and add to the hot liquid so much solution of 
platinum chloride as is equal to 20 grains of the metal. 
Evaporate this mixture on the water-bath nearly to dryness; 
that is, to the point when the thick syrupy liquid, on the 
momentary removal of the dish from the bath, passes into 
an orange-colored pasty mass. At this point remove the dish 
from the bath, and at the same instant, and before the dish 
and its contents have had time to cool, drench it with 500 to 
600 grains of rectified methylated spirit, containing about 15 
per cent, of water and 85 of alcohol; mix rapidly by impart¬ 
ing a rotatory motion to the contents of the dish ; then 
cover it and allow it to digest for five minutes. Have a 
filter ready, not too small, of 400 to 500 grains capacity, in 
a funnel with a cover: wash the filter first with hot water, 
and then with spirit, and after a short digestion pour the 
alcoholic solution of the platinum salts on to the filter, drain¬ 
ing the crystalline solid scales of the potash salt as dry as 


120 


GLASSM AKERS’ HAND-BOOK. 

possible, and again drench, agitate, and digest the insoluble 
salt with spirit; repeat this a third time, when the spirit 
will come away nearly colorless. Now collect the light 
orange crystalline scales of the potash platino-chloride on 
the filter, by means of a wasli-bottle, and, if need be, wash 
with spirit until it passes perfectly colorless. It is very ad¬ 
visable to wash the potash platino-chloride by decantation, 
and finally by a stream of spirit from a wash-bottle, to avoid 
the use of stirrers so as to prevent the scales being broken 
down, and to keep both dish and funnel lightly covered till 
the washing is completed. 

There is now nothing more to be done than to dry and 
weigh the potash platino-chloride, and to ignite and weigh 
the filter and add this to the weight of the salt. Owing, 
however, to the crystalline nature of the salt thus obtained, 
but a slight stain adheres to the filter, so that the loss by 
ignition is very minute and does not effect the result. As 
this crystalline precipitate is not liygrometric, its weight is 
easily and accurately determined. 

In this process the following points must be chiefly at¬ 
tended to:— 

I. Dilution of solution. 

II. Use of platinum chloride in large excess, about 20 
grains of metallic platinum to 10 grains of the salt examined. 

III. Heating of solutions, and evaporation so conducted 
as to obtain the potash salt in a crystalline scale-like condi¬ 
tion. 

IV. Evaporation on water-bath to a pasty condition—no 
further. 

V. Drenching with spirit whilst the salt and dish are 
hot, and instantly on removal from water-bath. 

VI. Washing by decantation, and avoiding breaking 
down of the crystalline precipitate. 

In practice, the process is a rapid one, from beginning to 
end requiring about two hours; less time, indeed, than is 


glawmakers’ hand-book. 


121 


frequently expended in merely washing tlie dense pulverulent 
precipitate which is obtained by the usual mode of manipu¬ 
lation. 

The results are very accurate. The authors take 244.20 
as the equivalent of the potash platino-chloride. 

Many modifications of the above described process have 
been proposed. 

It has been found that the determination of potash by 
platinum chloride is the more inaccurate the more foreign 
salts, such as sodium chloride, are present. The result ob¬ 
tained is generally too high, since the sodium platino-chlo¬ 
ride, if it has become too dry, can no longer be entirely 
removed by washing with alcohol. 

Precht conducts the determination of potassium as fol¬ 
lows :—The sulphuric acid is removed by barium chloride 
in a solution containing 0.5 of hydrochloric acid to 1 of the 
salt. The clear liquid should contain neither barium chlo¬ 
ride nor sulphuric acid. Traces , of the latter may be re¬ 
moved in the measuring vessel by finely pulverized barium 
chloride. Small quantities of sulphuric acid are admissible 
if the solution with platinum chloride is not evaporated 
quite to dryness. In acid solutions the objection to the re¬ 
moval of sulphuric acid by means of barium chloride, viz. : 
that alkalies are carried down along with the barium sul¬ 
phate, has little foundation. 

In neutral solutions so much potash sulphate is thrown 
down that an error of 1 per cent, may be occasioned. In 
evaporating down with platinum chloride care should be 
taken that large crystals of sodium platino-chloride are not 
formed, which would interfere with washing. The latter 
process is best performed with hot alcohol, there being no 
danger of the reduction of the platinum. A mixture of 
alcohol and ether is not to be recommended, nor an addition 
of glycerine. For the determination of small quantities of 
potash chloride along with an excess of sodium chloride. 


122 


GLASSMAKERS’ HAND-BOOK. 


Precht evaporates 10 to 100 grams along with a solution of 
sodium platino-chloride of known strength. The potassic 
salts are thus thrown down, the excess of the sodium com¬ 
pound is washed away with the absolute alcohol, the plati¬ 
num reduced on the filter and weighed. 

The committee appointed by the chemical section of the 
British Association reports that (1) potash in the form of 
pure chloride can be determined with great accuracy by 
precipitation as platino-chloride. If a large excess of plati¬ 
num solution be employed, and alcohol only used for wash¬ 
ing the precipitate, the results have a tendency to exceed the 
truth. By avoiding the use of a large excess of platinum 
solution more accurate results are obtained. If a small vol¬ 
ume of platinum solution be employed in the first instance 1 
for washing the precipitate (as recommended by Tatlock), 
and the washing then completed with alcohol in the usual 
way, the results are very accurate. Potash platino-chloride 
appears to be practically insoluable in concentrated solution 
of platinum chloride. 

(2) In presence of a considerable proportion of sodium 
chloride, washing the precipitate with with alcohol alone, 
tends to give results in excess of* the truth. If the precipi¬ 
tate be first treated with platinum solution the results are 
somewhat low, apparently owing to the solubility of the 
precipitate in solutions of sodium platino-chloride; the error 
increases with the amount of sodium, but is never very 
large, and a correction may be applied if desired. 

(3) If Tatlock’s method be employed, there is no occasion 
to separate any sulphates, nitrates, or magnesium; but if 
the amount of chloride present is insufficient for the exist¬ 
ence of all the potash as potash chloride, the deficiency must 
be supplied by the addition of sodium chloride or hydro¬ 
chloric acid. The results obtained are in many cases very 
accurate, but have a tendency to be somewhat below the 
truth. 


GLASSM AKERS’ HAND-BOOK. 


123 


(4) There is practically no advantage in drying potash 
platino-ehloride at 130° C. rather than at 100° C.; the loss 
at the higher temperature was found to exceed 0.07 percent, 
ot the weight ol the precipitate, but is probably governed 
by the conditions of precipitation. 

(5) The committee is of opinion that a preliminary wash¬ 
ing of the precipitate of potash with a solution of platinum 
chloride in a valuable modification of the usual process. As 
the method so modified is capable of direct application to 
the commercial potash salts, and does not necessitate the 
removal of sulphates, nitrates, or magnesium, the committee 
considers that it deserves to be generally applied to the de¬ 
termination of potash in commercial products containing 
it. 


Mr. K. Tatlock’s modification of the platinum process 
above referred to as follows :—Dissolve 35 grams of the sam¬ 
ple in water, filter if necessary and make up the bulk to 
500 c.c. Deliver 10 c.c. of the solution into a small porce¬ 
lain basin, add 20 c.c. of water, stir, and then add 30 c.c. of 
a solution of platinum chloride containing 7 grams of metal¬ 
lic platinum in every 100 c.c. Evaporate on water bath, 
but not to perfect dryness. Add a few drops of water and 
evaporate again ; remove the basin and stir the precipitate 
Avell with 2 c.c. of the platinum solution : then wash the 
precipitate on the filter with 1 c.c. more. Now wash the 
basin and filter and contents with the smallest possible 
quantity of alcohol of 95 per cent. Dry the filter contain¬ 
ing the precipitate on the water bath : remove the precipi¬ 
tate as completely as possible into a small platinum capsule; 
dry at 100° 0. and weigh. Ignite the filter with trace of ad¬ 
hering precipitate ; weigh the residue ol Pt x 2 (IvCl) which 
is left; calculate its weight of 2 (KC1) PtGU, and add the 
weight to that of the precipitate already obtained. 

The process employed at LeopokPs-hall and Stassfurt is 
described by Drs. Zuckschwerdt and West as follows :—10 


124 


GLASSMAKERS* HAND-BOOK. 


grams of a well-mixed sample are dissolved in a 500 c.c. 
flask filled up to the mark, shaken, an aliquot part filtered, 
and 20 c.c. (=0.4 gram) measured off. This is mixed in a 
porcelain capsule with 7 c.c. of a solution of platinum chlo¬ 
ride, containing 10 grams of platinum in 100 c.c. 

As commercial samples rarely contain more than 20 per 
cent, of sodium chloride, whilst the above quantity of plati¬ 
num would suffice for 0.4 gram of sodium chloride at 100 
per cent., there is always a considerable excess of platinum 
chloride present. 

The contents of the capsule are then evaporated on the 
water-bath with frequent stirring to the consistence of syrup, 
so that when cold the mass appears dry. The free hydro¬ 
chloric acid is thus chiefly expelled. When cold the mass 
is covered with 10 c.c. of alcohol at 95 per cent., well rubbed 
up with a glass rod, and the washings are poured upon a 
balanced filter. Alcohol is again spirited on in small quan¬ 
tity ; the mass is again rubbed up, the washings poured off, 
and the operation is reported once more. As a rule, at the 
second decantation the color of the washings, and conse¬ 
quently the proportion of the platinum double salt, will be 
very slight, and in the third operation it disappears alto¬ 
gether ; otherwise the operation must be repeated once 
more. The precipitate, which now consists of perfectly pure 
potash platino-chloride, is brought upon the filter, by means 
of the alcohol washing-bottle; and after drying for half an 
hour at 110° to 115°, it is weighed under the same condi¬ 
tions as it had been when empty. 

The total quantity of alcohol consumed is in general 55 
c.c. The errors fall within the narrowest limits of permissi¬ 
ble experimental errors, and could scarcely be removed or 
avoided by greater complication. 

MM. Corenwinder and G-. Coutamine add to the portion 
taken for analysis a slight excess of hydrochloric acid, and 
then, without taking any notice of the possible presence of 


GALSSM AKERS’ HAND-BOOK. 


125 


sulphuric acid, silica, or phosphoric acid, they evaporate in 
the water-bath, after having added a sufficiency of platinic 
chloride. The potash platino-chloride thus obtained is di¬ 
gested with alcohol at 1)5°, mixed with ether, and washed in 
the ordinary way with the same liquid. When this opera¬ 
tion is complete, boiling water is poured upon the filter by 
means of a pipette, till the platino-chloride is entirely dis¬ 
solved, and the filtered liquid is collected. Water contain¬ 
ing sodium formiate is then heated, and while it is boiling 
the preceding solution of potash platino-chloride is carefully 
poured into it by degrees. In a few moments the platinum 
is thrown down as a black powder, which merely needs to 
be washed, dried, heated to redness, and weighed in order to 
find the quantity of potash present in the sample. 

Dr. F. Mohr estimates potash by titrating the chlorine 
contained in the platino-chloride. He decomposes this salt 
by fusing it in a platinum crucible, with twice its weight of 
sodium oxalate. After lixiviation tin 1 chlorine is determined 
by a decinormal silver solution. 

M. L. de Koninck throws down potash with the ordinary 
precautions by platinum chloride; the precipitate is collected 
on a filter, washed in alcohol, and immediately dissolved in 
boiling water. The solution is reduced hot by magnesium. 
All the chloride of the platino-chloride is obtained in the 
form of a soluble chloride and a black precipitate of reduced 
platinum. At the same time the magnesium decomposes 
the water, yielding hydrated magnesia with an escape of 
hydrogen. When the reduction is complete tin* mixture is 
filtered, and in the neutral solution the chlorine is deter¬ 
mined in the usual manner with a standard solution of silver 
nitrate, using potash chromate as indicator. 


126 


GLASSMARERS’ HAND-BOOK. 


SODIUM. —Analysis of Salt Cake. 


The method preferred for the examination ot salt cake, 
black ash, soda ash, and other commercial products of the 
alkali manufacture, is that given by Dr. C. R. A. \\ right, 
F. R. S. Ordinary salt cake is valued according to the per¬ 
centage of available sodium sulphate contained; i. e., the 
percentage of sodium sulphate existing mainly as such, and 
partly as sodium bisulphate. The mode of estimation of 
the available sulphate usually pursued is the following: 

1. The sodium chloride is determined volumetrically by 
a standard silver solution. 

2. The quantity of a standard alkaline solution required 
to render a known weight of salt cake exactly neutral to 
test papers is determined, and the result sometimes calcu¬ 
lated as anhydrous sulphuric acid, sometimes as lrionohy- 
drated sulphuric acid, called “ free acid." 

3. The difference between the sum of the two previous 
determinations and 100 is assumed to be “ available sodium 
sulphate,” 

By this mode of proceeding errors of one to three or more 
per cent, are introduced; ordinary salt cake containing, in 
addition to sodium sulphate, bisulphate and chloride, per¬ 
ceptible quantities of lead sulphate, iron, persulphate, iron 
sesquioxide, calcium sulphate, magnesium sulphate, moisture, 
and particles of sand, brick, etc., derived from the furnace 
during the manufacturing process. Where a greater degree 
ot accuracy is desirable, a known weight of salt cake may 
be treated with water, ammonia and ammonium oxalate 

added to the unfiltered solution, and the precipitated iron 

> 

sesquioxide and calcium oxalate, with the insoluble matters, 
weighed after ignition : by moistening the ignited precipitate 
with pure sulphuric acid, and igniting again, the calcium 
oxalate is converted into calcium sulphate, and then the 
weight of the mixed substances indicates all the “impurities” 



GLASSMAKERS’ nAND-BOOK. 


127 


present in the salt cake; with the exception of the mag¬ 
nesium sulphate, which rarely amounts to more than traces, 
and the moisture, which is occasionally a very perceptible 
quantity, especially in samples that have been made some 
lenth of time. 

The amount of iron persulphate present depends on the 
degree of heat to which the salt cake has been subjected 
during manufacture. In highly-roasted samples, cold water 
yields a solution containing no iron whatever, all the iron 
present in the salt cake consequently existing as sesquioxide; 
specimens of under-roasted salt cake, on the other hand, 
when treated with cold water, leave only fragments of brick, 
calcium sulphate, &c., undissolved, all the iron existing as 
persulphate. In ordinary salt cake, however, there is so 
littlo ferric sulphate that no perceptible error is committed 
in assuming that all iron present exist as sesquioxide, and 
all the “ free acid ” as sodium bisulphate. Accordingly, the 
following methods have been found to give tolerably expe¬ 
ditiously the exact composition of such salt cake: 

(a) A known weight, 5 or 10 grams, is dried at 110 — 
120° C., till constant in weight; too great elevation of tem¬ 
perature being avoided to prevent any possible loss of hy¬ 
drochloric acid by reaction of the sodium bisulphate on the 
sodium chloride present. 

(b) The sodium chloride is determined volumetrically by 
a standard silver solution. 

(c) A solution of sodium hydrate free from carbonate, or 
of caustic ammonia, of known strength, is added to a known 
weight of salt cake until test papers indicate exact neutral¬ 
ity . of the liquid ; the alkaline solution used accordingly 
corresponds to the iron persulphate and sodium bisulphate 
together, and may therefore be safely calculated as the 
latter. 

(d) A known weight of salt cake is boiled with an excess 
of a standard sodium carbonate solution, and filtered; the 


GLASSM AKERS* HAND-BOOK. 


128 

unneutralized alkali in then determined by a standard acid 
solution. The amount of alkaline solution neutralized by 
the salt cake indicates the calcium sulphate, sodium bisul- * 
phate, and iron persulphate together; and hence the differ¬ 
ence between (c) and (d) indicates the calcium sulphate. Or 
the calcium sulphate may be determined gravimetrically by 
precipitation with ammonium oxalate, after separation of 
the iron sesquioxide by ammonia from the solution of a 
known weight of salt cake in hydrochloric aeid. 

(e) The precipitate thrown down in (c) may be collected 
and boiled with hydrochloric acid ; the insoluble sand, &c., 
may be weighed, and the ferric salt reduced by zinc or other 
reducing agent, and titrated volumetrically by permanga¬ 
nate or otherwise. 

(f) When the lead sulphate is to he determined, it may be 
done by treating a considerable quantity, say 20 grams, with 
water, and boiling the insoluble residue with strong hydro¬ 
chloric acid till the lead sulphate is entirely dissolved ; from 
this solution lead sulphide may be thrown down by sulphu¬ 
retted hydrogen, and the lead determined in the ordinary 
way. 

(g) If magnesium sulphate is to be determined, it may be 
done by dissolping a known weight, say 20 grams, in hydro¬ 
chloric acid, adding ammonia and ammonium oxalate, and 
precipitating the magnesium from the filtrate by a phosphate, 
and ultimately weighing the magnesium pyrophosphate. 

(h) If the preceding determinations have been carefully 
conducted, the difference between 100 and the sum of them 
may be safely taken as sodium sulphate; if this is to be di¬ 
rectly determined, however, it may be done either by deter- 
mining the total sulphuric acid present by dissolving a known 
weight of salt cake in hydrochloric acid, and precipitating 
by barium chloride, and weighing the barium sulphate ; sub¬ 
tracting the sulphuric acid, contained as calcium sulphat, 
sodium bisulphate, magnesium sulphate, and lead sulphate, 


GLASSMAKERS’ HAND-BOOK. 


129 


the remainder being calculated as sodium bisulphate; or by 
adding ammonia and ammonium oxalate to the aqueous 
solution ot a known weight, and estimating the residue left 
on evaporation ot the filtrate and ignition with sulphuric 
acid ; on subtraction from this of the amounts due to mag¬ 
nesium sulphate, sodium chloride, and sodium bisulphate, 
the sodium sulphate is directly ascertained. 

The total “available sodium sulphate” is known by adding 
71-120 of the sodium bisulphate to the amout of sodium 
sulphate found. 

Mr. W. Tate proposes the following method for the analy¬ 
sis of salt cake : The free sulphuric acid and undecomposed 
salt are determined by standard solutions of sodium carbon¬ 
ate and silver nitrate respectively; calcium sulphate by 
ammonium oxalate; silica, and iron peroxide, by precipita¬ 
tion by ammonia or sodium acetate; and moisture, by dry¬ 
ing at 100° C. 

Another method, which is favored by the “high” analyst, 
differs from the above, inasmuch as the “free acid and mois¬ 
ture” are estimated together by the loss of weight on igni¬ 
tion or roasting of a sample. Now it is clear that the result 
of ignition must be that a portion of the free sulphuric acid 
will react on part of the salt, forming sodium sulphate and 
liberating chlorhydric acid. Thus the analyst performs a 
manufacturing operation in the process of his analysis, 
and his “results” represent a higher percentage of sodium 
sulphate than is really present in the original sample. And 
the amount of his error varies with the composition of the 
sample. 


SODA ASH. 


The commercial valuation of soda ash is usually restricted 
to the determination of the percentage of “ available al¬ 
kali ” contained therein, by this term being meant the total 



130 GLASSMAKERS’ HAND-BOOK. 

sodium oxide (anhydrous) contained in a state capable of 
saturating a strong acid, as sulphuric; and lienee including 
hydrate, carbonate, aluminate, silicate, sulphide, sulphite, 
and thiosulphate. The analysis is usually performed by 
adding the standard acid to the hot aqueous solution of a 
known weight of ash, until a slight acid reaction is obtained ; 
by this means all the lime and the alumina contained as 
aluminate are estimated as though they were soda. Prac- 
tically this error is of slight importance ; it may be readily 
avoided by addition of a very slight excess of acid along 
with some tincture of litmus, then adding a slight excess of 
standard sodium carbonate solution, boiling and filtering 
from the precipitated lake and calcium carbonate; the ex¬ 
cess of sodium added is now again determined by the stand¬ 
ard acid, and thus the exact amount of acid used to saturate 
the sodium oxide present in the “ available ” state is known. 

Mr. Pattinson, of Newcastle-on-Tyne, has lately drawn 
public attention to a strange error made by some analysts 
in attempting to apply the English commercial test for soda 
to samples of alkali, soda ash, etc., the result of which error 
is to make the test indicate from 1 to 1] per cent, more soda 
than the sample contains by the proper English test. It is 
well known that the English soda test had its origin in the 
early days of the soda trade—when chemists believed the 
equivalent of soda to be 32, and that of sodium carbonate 
54; and consequently, test acid was made so that 40 parts 
of sulphuric acid neutralized 54 parts of sodium carbonate, 
equal to 32 of soda. This method .of testing has always 
been, and still is, used by the soda trade throughout Eng¬ 
land ; and it is a custom well understood by both buyers and 
sellers. It indicates 0.66 per dent, more soda in a 50 per 
cent, alkali than the rigidly-correct test based on the new 
equivalent 31 would indicate. It is certainly desirable, for 
the sake of scientific accuracy, that the correct equivalent, 
31, should be used in testing; but, seeing that manufactu- 


GALSSMAKERS* HAND-BOOK, 


i:n 


rers have expended their capital in plant, and made their 
contracts for their various materials on the understanding 
that a product containing a certain percentage of soda would 
be obtained, and seeing that there arc? other commercial cus¬ 
toms of the trade still in force, which tell as much against 
the manufacturer as the test does in his favor—much, for 
instance, as that of not charging for fractions of percentage 
—it is more the province of an association like the Alkali 
Manufacturers’ Association than that of an analytical chem¬ 
ist to make alterations in trade usages affecting such vast 
interests. Certainly, if any alterations be. made at all by 
chemists, it should be made in the direction of scientific ac¬ 
curacy, and not in the contrary direction, as in the case 
above referred to. The error arises in this way : the test 
acid is made so as to indicate the exact amount of soda ac¬ 
cording to the new and correct equivalent 81—that is, that 
40 parts of sulphuric acid should neutralize 53 parts of so¬ 
dium carbonate, equal to 31 parts of soda. 

To convert the results obtained by this test acid into the 
English commercial soda test, it is incorrectly assumed that 
the 31 parts of soda are equal to 32—in other words, that 
the 53 parts of sodium carbonate contain 32 parts of soda. 
This is where the error lies: for, according to the correct 
English test, 54 parts of sodium carbonate, and not 53, con¬ 
tain 32 of soda; and, therefore, bv the English test, 53 parts 
of sodium carbonate contain only 31.41 of soda. By thus 
mixing up the old and the new systems of equivalents, a 
sample of soda ash which, by the correct English test, con¬ 
tains 50.6(1 per cent., would be returned as containing 51.61 
per cent, of soda. A sample of caustic soda which, by the 
correct English test, would contain 75.0 per cent, of soda 
would, by this erroneous method, indicate 76.4 per cent. It 
is only necessary to point out this error in order that it maj 
be avoided and guarded against by anyone interested in the 
buying and selling of alkalies. 


l:>2 


GLASSMAKERS’ HAND-BOOK. 


When the exact composition of a sample of soda ash is 
required, the following method may be adopted : 

(a) A known weight is heated to 150°—200° C., and the 
loss of weight considered to be moisture. 

(b) The residue of ( a) treated with hydrochloric acid leaves 
sand and insoluble matter, and in the filtrate the sulphuric 
acid may be estimated volumetrically, or, better, gravimet- 
rically by barium chloride. 

(c) The carbonic acid present is estimated in Mohr’s ap¬ 
paratus, or in Fresenius and and Will’s, with the addition 
of some potassium chromate. 

(d) A known weight is treated with water, and the solu¬ 
tion evaporated to dryness with hydrochloric acid ; thus the 
silica is determined : in the filtrate from this ammonia throws 
down alumina, from which the aluminum, as aluminate is 
known. 

(e) The insoluble residue of (d) with hydrochloric acid 
and ammonia gives the iron and alumina (not as aluminate); 
the filtrate from this with ammonium oxalate gives the 
calcium (usually only traces). 

(f) A known weight is dissolved in nitric acid, and the 
chlorine estimated by a standard silver solution. 

(g) A known weight dissolved in water is oxidized by 
chlorine, and the sulphate thus formed determined ; another 
known weight is dissolved in water and the solution divided 
into two equal parts; in one the iodine required to yield a 
blue color when starch and acetic acid are added, is de¬ 
termined, to the other zinc sulphate is added, and in the fil¬ 
trate the iodine required after removal of the precipitated 
zinc sulphide is again determined; from these data the sul • 
pliide, sulphite, and thiosulphite are calculable. 

(h) The total “ available alkali ” is determined, the error 
due to the aluminum of the aluminate being eliminated as 
previously mentioned; subtracting from this, calculated as 
sodium, the sodium corresponding to the silica, alumina, 


GLASSMAKERS’ HAND-BOOK. 


133 

sulphide, sulphite, thiosulphate, and carbonic acid found, 
the difference is calcu'ated as hydrate; this may be 
checked by adding barium chloride to a known weight, and 
determining the amount of acid required to neutralize the 
filtrate ; rather more hydrate is usually indicated by this 
mode than what is really present, owing to the presence of a 
portion of aluminate, thiosulphate, ike., incompletely thrown 
down by the barium salt. 

Carefully executed analyses according to this method have 
yielded results adding up to between 99.8 and 100.1. 

When ferrocyanide is present, it may be estimated by 
dissolving a known weight of ash in hydrochloric acid, and 
adding iron perchloride ; after standing some time, the pre¬ 
cipitated Prussian blue may be well washed, treated with 
pure potash, and the ferrocyanide determined in the solu¬ 
tion by permanganate. 

M. Jean has proposed a somewhat different method of 
analyzing soda ash and caustic soda. His process, which, 
although it does not give quite so accurate results as those 
already described, may occasionally be found useful, is as 
follows: Take 4 grams of the sample to be analyzed, and 
dry completely at from 110° to 120° C. ; the difference be¬ 
tween the weight of the quantity originally taken and the 
weight after drying gives the quantity of water. Take 1 
gram of this dried material, place it in a glass tube, and pass 
a current of dry carbonic acid gas over the substance for 
about an hour; dry it again at 110°, to drive off any me¬ 
chanically-adhering carbonic acid; place the substance upon 
a filter, and exhaust with tepid water, until the wash water 
is no longer precipitated by barium chloride. 

The filtrate is collected in a glass flask with flat bottom, 
and barium chloride is added to it. The liquid is left to 
settle, and, on having become quite clear, is drawn off from 
the precipitate by means of a pipette, and the precipitate of 
barium carbonate is collected on a tared filter, washed with 


1 :u 


GLASSMAKERS* HAND-BOOK. 


boiling water, dried, and weighed. If there happens to be 
sulphates present, the sulphuric acid is precipitated, along 
with the barium carbonate, as barium sulphate; and the 
weighed barium carbonate is, therefore, wash water acidu¬ 
lated with hydrochloric.acid, again washed witli warm water, 
and, after drying, weighed. 

In order to estimate the sodium carbonate, 1 gram of the 
dried sample is taken, dissolved in water, precipitated with 
barium chloride; the precipitate is collected on a tared 
filter, and after having been washed and dried, the weight 
of the barium sulphate is deducted from the weight found. 
The difference of the weights of the barium eorbonates 
found by these two operations indicates the quantity of 
barium carbonate which, h}' calculation, has to be converted 
into caustic soda; the Second assay gives the quantity of 
sodium carbonate. In order to estimate the sodium sulphide 
contained, 1 gram of the dried material is again taken; this 
quantity is dissolved in water, and estimated according to 
the following process. 

ESTIMATION OF SOLUBLE SULPHIDES IN COM¬ 
MERCIAL SODA AND SODA ASH. 


These may be readily estimated by the following method, 
based on the insolubility of silver sulphide, and the solu¬ 
bility of all the other argentiferous salts, in presence of am¬ 
monia. The process was originally devised by If. Lestelle. 

Prepare a normal solution of ammoniacal silver nitrate by 
dissolving 29.69 grams of line silver in pure nitric acid, 
adding 250 c.c. of ammonia, and diluting with water to 
bring the volume to 1 litre. Each c.c. of this solution cor¬ 
responds to 0.01 gram of sodium monosulphide. 

Dissolve- the substance to he analyzed in water, add am- 

monia, boil, and then add, drop by drop, by means of a 

burette divided into tenths of a c.c., the ammoniacal silver 
• ' 



GLASSMAKERS’ HAND-BOOK. 


135 


solution, and a black precipitate of silver sulphide takes 
place. When nearly all the sulphur is precipitated, filter, 
and into the filtered liquid pour a fresh quantity of silver 
solution, until, after repeated filtrations, a drop of this liquid 
produces only a slight opacity. The estimation is then at 
an end, and it is only necessary to read the divisions indi¬ 
cated by the burette, and to convert this number into the 
corresponding amount of sodium sulphide. 

To estimate very small quantities of sulphide, the argen¬ 
tiferous liquid must be more diluted, so that each c.c. cor¬ 
responds to 0.005 gram of sulphide. The presence of chlor¬ 
ide, sulphate, and sodium carbonate, caustic soda, etc., makes 
uo difference in the accuracy of this method, by reason of the 
solubility in ammonia of the precipitates given by these 
bodies with silver nitrate. 

SEPARATION OF POTASH FROM SODIUM. 


To separate potash from sodium when in presence of sul¬ 
phuric acid, Finkener proposes the following:—Add hydro¬ 
chloric acid to the aqueous solution to be analyzed : then 
solution of platinum chloride until the liquid is deep yel¬ 
low. Add water sufficient, when boiling, to dissolve the 
double salt precipitated ; evaporate to syrupy consistence, 
but do not dry ; extract, and wash on a filter with a mix¬ 
ture of alcohol (specific gravity 0.8) 2 volumes, ether 1 vol¬ 
ume. Wash well with solution of ammonium chloride; 
this decomposes the sodium sulphate and allows it to be 
washed away. The filtrate, alcoholic extract, and washings 
contain the sodium. Heat the filter and its contents in a 
stream of hydrogen—a temperature of 240° suffices ; extract 
the potash chloride with water, and weigh, or titrate with 
solution. 

A great excess of sulphuric acid is to be avoided. I he 
ammonium chloride solution dissolves about 0.13 to 0.26 per 



GLASSM AKERS* HAND-BOOK. 


13(3 


cent, of the potash platino-chloride, hut the quantity so lost 
varies with the strength of the solution, its temperature, and 
the quantity of free hydrochloric acid in it. On the other 
hand, the double salt carries down with it about 0.1(3—or 
0.35 per cent, of sodium salt. 

INDIRECT ESTIMATION OF POTASH AND SODIUM. 


The direct method of estimating potash and sodium—viz. 
by the precipitation of the former as potash platino-chloride, 
and reckoning sodium from the loss—though sufficiently 
accurate in patient and skillful hands, is yet open to many 
sources of error, and at the best is exceedingly tedious and 
troublesome. 

The indirect method does not appear to possess the confi¬ 
dence of chemists—at least, it is rarely mentioned in pub¬ 
lished investigations, Mr. P. Collier, B. A., Assistant in the 
Sheffield Laboratory, Yale College, U. S. A., has published 
a number of experiments to ascertain the limits of error 
in this process.* 

The volumetric estimation of chlorine as perfected by 
Mohr offers by far the best basis for an indirect determina¬ 
tion of the alkalies. It is, in fact, requisite, in employing 
the usual direct method, to procure the alkalies in the con¬ 
dition of pure chlorides before precipitation. 

When the alkaline chlorides are obtained free from all 
foreign matters, it is but the work of a few moments to as¬ 
certain their contents of chlorine. 

The silver solution used for this purpose is best prepared 
by weighing off in a porcelain crucible about 4.8 grams of 
clear crystallized silver nitre, fusing it at the lowest possible 
heat, and then ascertaining it's weight accurately. After 
fusion it should weigh a little more than 4.7933 grams, the 
quantity that, contained in a litre of water, gives a solution 
of which 1 c.c.=0.001 gram of chlorine. The fused salt is 

♦American Journal of Science, xxxvii, 344. 




GLASSMAKERS 7 HAND-BOOK. 


137 


dissolved in a little warm water, the solution brought into a 
litre flask and filled to the mark, observing the usual pre¬ 
cautions as to temperature, etc. When thus adjusted, add 
to the contents of the bask, from a burette, enough water to 
bring the excess of silver nitrate above 4.7933 grams to the 
requisite dilution. In this way.it is easy, with a burette and 
litre flask, to make a perfectly accurate standard solution, 
while this would be hardly possible should the operator 
weigh off* less than 4.7933 grams of silver nitrate. 

This solution, which may be preserved in a well-stoppered 
bottle indefinitely, without change, is next tested by means 
of a solution of pure sodium chloride or ammonium chloride; 
a quantity, say about 2 grains, of one of these salts being 
dissolved in a litre of water and 10 c.c. of the liquid taken 
for the comparison. The solution being ready, the estima¬ 
tion of chlorine is conducted as described by Mohr, Fresinus, 
Sutton, and others, potash chromate being employed to indi¬ 
cate the completion of the reaction. The use of Erdmann’s 
float in a burette (which may hold 70 c.c.) graduated to fifths 
ensures the needful accuracy of reading. Two-tenths c.c. of 
silver solution may be deducted as the excess needed to 
produce a visible quantity of silver chromate. 

From a long list of analysis given by the author, it is 
shown that the indirect method is in all cases equal in accu¬ 
racy to the ordinary separation, while in the matter conve¬ 
nience and economy of time there is no comparison between 
them. In no case does the difference between the quantities 
taken and found of either alkaline chloride exceed two mil¬ 
ligrams, and in most instances it is less than one milligram. 
The correspondence between the amounts of chlorine as 
taken and found is, of course, still more near. The error 
that appears in the estimation of the chlorides would be 
considerably reduced, if as usually happens, the metals were 
calculated as oxides. 


1.°,8 


GLASSM AKERS’ HAND-BOOK. 


RAPID ESTIMATION OF POTASH AND SODIUM. 


M. Jean grinds np the saline mixture, in which it is de¬ 
sired to determine the potash and soda, with an excess of 
ammonium sulphate, moistened with a few drops of water, 
heated to redness in a platinum crucible till the ammoni- 
acal salts have completely disappeared, and heated once 
more with ammonium sulphate in the same manner, so as to 
ensure the expulsion of all acids capable of displacement by 
sulphuric acid. The substance is then dissolved in boiling 
water, a slight excess of baryta water is added, and the sul¬ 
phates and insoluble matters are removed by filtration. The 
filtrate is then treated with a little seltzer water, and kept 
at a boil till all excess of carbonic acid lias been expelled, 
and all the barium carbonate rendered insoluble. The solu¬ 
tion is then filtered, when the potash and soda remain in the 
filtrate in the state of carbonates, and are exactly neutral¬ 
ized with a standard solution of hydrochloric acid at the 
boiling point. In this neutral liquid the weight of the chlo¬ 
rides present is determined by bringing the solution—by 
evaporation or by the addition of water, as the case may be 
—to a volume of 50 or 100 c.c., the specific gravity of which 
in then determined; or the solution may be evaporated to 
dryness, and the residue may be weighed. Knowing, there¬ 
fore, from the quantity of hydrochloric acid used in filtra¬ 
tion, the weight of chlorine corresponding to the two alka¬ 
lies and the weight of the two chlorides, it is easy to calcu¬ 
late the proportions of potash and soda. If the chlorine 
found is multiplied by 2.1029, the weight of the chlorides 
subtracted from the product, and the remainder multiplied 
ba 3.6288, we obtain the weight of sodium chloride, whilst 
the difference will be the potash chloride. If it is required 
to determine alkalies in presence of a superphosphate, it is 
prudent to neutralize with baryta water before adding am¬ 
monium sulphate to prevent the formation of pyrophos¬ 
phates. 




139 


GLASSM AKERS* HAND-BOOK. 


M. F. Maxwell Lyte proposes the following indirect 
method for determining potash and soda:—Having obtained 
the mixed sulphates free from any other salts, and in solu¬ 
tion, evaporate the mixture to dryness, heat to redness and 
weigh. Now redissolve the salts, and estimate the percent¬ 
age of sulphuric anhydride they contain by any convenient 
volumetric or gravimetric method, and from the percentage* 
thus found subtract the percentage of sulphuric anhydride 
the salt would contain were it pure potash sulphate. The 
figures 45.977 are a sufficiently close approximation to this 
last-named percentage, and by simply multiplying the re¬ 
mainder by 9.66, the result will be* the percentage of sodium 
sulphate the mixed salts contained. 

This result is not absolutely correct, for the multiplier is a 
little too high, but the error is not 1.00001, which is near 
enough for all practical purposes. 

The result obtained deducted from 100, the remainder will 
be ther percentage of potash sulphate, and from these results 
the quantities of each of the alkalies sought may be calcu¬ 
lated. 


SILVERING GLASS. 


Silvering plate glass is produced by causing a slight 
coating of mercury to adhere to the glass. To obtain this 
result mercury must be retained by a metallic medium ; it is. 
therefore, amalgamated with tin. Mercury, owing to its 
power of reflecting light very brightly, has been chosen as the 
best medium. 


The operation of silvering is briefly as follows: 

Upon a very smooth stone table a sheet of very thin tin is 
spread very carefully, so as to prevent all wrinkles. Upon 
this sheet mercury is rubbed all over, then as much mercury 
as the sheet will retain is poured over it. The glass plate is 
now carefully slipped over the edge of the stone table, as near 



140 


GLASSM AKERS’ HAND-BOOK. 


as possible to the mercury, and lowered on to it. All the 
parts previous to this operation have been carefully cleaned, 
and the plate is handled with pieces of tissue paper, to pre¬ 
vent the introduction of dirt. The plate is now covered 
with a cloth and loaded with weights to expel the surplus 
mercury. When the plate has been so weighted, the table 
is slightly inclined, and gradually in creasing the inclination 
from time to time, until the mercury has been sufficiently 
drained; this generally requires twenty-four hours. The 
plate is now carefully taken up and carried over to an in¬ 
clined wooden table, which is depressed gradully more and 
more to finish draining the mercury until the plate is sup¬ 
posed to be dry. 

This is the process which has been heretofore followed 
altogether, but of late plates have been silvered with a 
solution of silver. Mercury has deplorable effects upon the 
health of workmen, as they are exposed to its dangerous 
emanations; these are rapidly absorbed by the skin and 
produce the well-known and terrible mercurial poisoning. 
It is hoped, therefore, that mercury will be abandoned, and 
the new silvering process described below will be adopted in 
its place. Several methods have been proposed for silver 
solutions, all springing, however, from the discovery of 
Liebig, that aldehyde (produced by a partial oxidation of 
alcohol) when heated with nitrate of silver, the revivified 
metal covers the glass with a brilliant metallic coating. It 
is not my purpose to trace the different improvements made 
by Drayton and Pettitjean, but I will briefly indicate the 
process of the latter, which is now altogether used by the St. 
Gobain works with perfect success. 

The operation is very similar to silvering with mercury. 
The table, instead of being a stone, is a hollow sheet iron 
table, made quite smooth on its upper surface, and contain¬ 
ing inside water capable of being heated by means of steam, 
to bring the temperature to 95—104 degrees. Preparatory 


GALSSM AKERS* HAND-BOOK. 


141 


to silvering the glass it should he thoroughly cleaned. The 
table being ready, a piece of oil cloth is spread over it, and 
upon this is laid a piece of cotton cloth. The plates are now 
put upon these cloths, and the following solutions are poured 
over them : 

Liquor No. 1. Dissolve in a litre of water 100 grams of 
nitrate of silver; add 02 grams of liquid ammonia of 0.880 
density; filter and dilute with sixteen times its volume of 
water. Then pour in this liquor 7.5 grams of tartaric acid 
dissolved in about 80 grams of water. 

Liquor No. 2. This liquor is precisely the same as the 
other, with the exception that the quantity of tartaric acid 
is doubled, say 15 grams. 

First pour of liquor No. 1 upon the plates as much as will 
remain upon the surface without running over. The heat 
of the table is now increased gradually to 05—104 degrees 
Fahrenheit, and in about thirty minutes the glass is covered 
over with a metallic coating. The table is now inclined and 
the plates washed with water, which carries off the surplus 
silver. The table is again raised, and liquor No. 2 is now 
poured over; in about a quarter of an hour another coat is 
deposited, which covers the glass completely. The plates 
are again washed; then they are carried to a slighly heated 
room, where they are gradually dried. 

This operation, as will be seen, is quite simple, and is gen¬ 
erally performed by women. The silver carried off in wash¬ 
ing and that contained in the cloths is recovered again. 
Since glass silvered by this process is liable to be altered 
when exposed to the air, and the coating may become easily 
detached if not covered over with a protecting coat of paint, 
the silver pellicle is covered with an alcoholic copal varnish, 
put on with a brush, and when this is dry a coat of red lead 
paint is put on. 

Plates silvered by this means have more brilliancy than 
with mercury, but as there is a slight tinge of yellow given 


142 


GLASSMAKERS* HAND-BOOK. 


to objects reflected by these mirrors, they were at first ob¬ 
jected to. This objection has passed away, bower, to a great 
extent, and the yellow reflection has been obviated by giving 
a slight coloration to the glass. 1 have not been able to get 
positively the relative costs of both processes; it is said, 
however, that the new silver process costs about 3b cents per 
square meter. Inasmuch as such works as the St. Gobain 
have adopted it, and as the terrible disorders caused by 
mercury may be thus avoided, there should be no hesitation 
in adopt! ing this process everywhere.’ 

STRASS, AND ARTIFICIAL GEMS. 


Strass, a heavy lead flint, the method of whose composi- 
was rediscovered by the Viennese' jeweler, Joseph Strasser 
(whence the name), is the base of all modern imitations of 
artificial gems. Anciently all glass, partly owing to the 
crude and inferior raw materials used, was, of necessity, 
colored. Pure, colorless, pellucid flint, is of more recent 
date, does not antedate the Roman Empire, as a rule, the 
oldest discovered piece of transparent glass being found by 
Layard at Nineveh, to which the date 722 B. C. has been 
affixed. 


Strass, a glass rich, very rich, in lead, forms the base to 
which all coloring matter in the manufacture of artificial 
gems is added. Its peculiarities consist in its large specific 
gravity, and its increased refractive power, it being most 
perfect in composition, as it nearest approaches these dis¬ 
tinctive features in the products of nature it is intended to 
imitate. 

German glassmakers once excelled the world in this 
branch of manufacture. Indeed, as before stated, one Joseph 
Strasser, a Viennese jeweler, rediscovered the ancient method 
of imitating precious stones, the fabrification of which has 
been secretly prosecuted during ages past; is noted by The- 



GLASSMAKERS’ HAND-BOOK. 


14 


o 

o 


ophilus and Seneca, and the history of which, ulteriorly, is 
" lost in the twilight of fable.” 

France, with the same determined devotion with which, 
more anciently, she wrested from Venice her secret methods 
of manufacturing mirrors, as early as 1819, encouraged 
Donault - Wieland with the first prize of the Societe 
d'encourgement to aid industry with laboratory research, 
and from thence dates the superiority of the products of 
I ranee in this jeweled sphere of human endeavor and 
industrial accomplishment. 

Formerly pure ground rock crystal was deemed indis- 
pensible in the production of artificial gems, but modern 
methods have so purified and cleansed sand that its purity 
is equal to crystal or quartz. Necessarily, all ingredients 
must be of the purest if the best results are to obtained. 

It is the general practice abroad to have all materials 

r 

chemically pure, and therefore they are subjected to the 
most scrupulous cleansing processes. 

The analysis of Dumas showed the constituents of I)onault- 
Wieland’s Strass to be: 


Silica. 

Lead. 

Potash. 

Alumina. 

Arsenic and borax 


1 2 3 


38.3 

32.9 

35.5 

53.0 

49.9 

53.9 

7.8 Soda.. 

.15.1 

8.3 

1.0 Borax 

. 0.6 

0.7 

trace 

1.5 

1.6 


100.00 100.0 100.0 


WENT UK IN, ANALYSIS OF. 




Hautefeuille. 

Levol. 

Peligot. 

Schne- 

der- 

mann. 

Kirsten 

Silica. 

61.6 

60.39 

60.66 

60.5 

67.7 

&5.2 

67.3 

Potash. 

Soda. 

| 21.0 

) 5.70 

J 11.31 

121.92 

22.ol 

5.5 

7.1 

2.1 

8.2 

5.3 

7.0 

Lime. 

5.9 

8.61 

8.63 

6.8 

8.9 

8.0 

9.0 

Magnesia. 

— 

0.08 




4.5 

— 

Alumina. 

2.3 

3.71 

— 

— 




Oxide of iron. 

4.2 

2.50 

4.90 

3.5 

3.5 

6.5 

3.7 

Manganese. 

— 

0.21 






Oxide of tin. 

— 

2.48 

— 

2.3 

2.3 

trace 

2.3 

Copper, metallic 
Oxide of copper. 

— 

— 

— 

3.9 

3.9 

— 

— 

5.05 

4.05 

4.8 



3.0 

5.0 

Oxide of lead. 

— 

0.69 



1.1 

— 

1.0 

Phosphoric acid 

— 

— 

-- 



1.5 












































144 


GLASSMAKERS’ HAND-BOOK. 


STRASS.— Donault-Wielaxd. 


Sand. 

Lead. 

Pearl ash, calcined. 

Borax, calcined. 

Arsenic.. 


100 

60 


300 

20 

2 



1 

2 

3 

4 

5 

6 

7 

Rock crystal. 

. 300 

300 



100 


100 

Lead. 

. 470 

462 




100 

154 

Lime (hydrate). 

Borax. 

. 163 

22 

168 

18 

96 

27 

105 

50 

156 

171 

Arsenious acid. 

1 

0.5 

1 

1 

54 

32 

56 

6 

White sand. 



300 

717 

7 

9 

White lead. 



514 

709 

3 

3 

16 


STRASS.- 

Loysel. 


1 

2 

3 


100 

70 


The specific gravity of the above is the same as that of the 
diamond. 

STRASS.— Bastenaikk. i 2 


Sand. 100 100 

Lead. -10 140 

Potash. 24 32 

Borax. 20 12 

Saltpeter. 12 Arsenic,0.6 

Manganese. 04 - 

STRASS.— Base for Colored, Bastenaike. 

3 4- 5 

Sand. 25 25 25 

Lead. 50 60 55 

Potash. 7 Borax.5 8 

Saltpeter. 8 Arsenic, 1-16 — 1 /> Saltpeter, 8 

Manganese, 1-10 


OPAL.— Bastenaike. 


Sand... 
Lead... 
Potash 


Zb 

20 

10 


Saltpeter. 2 

Oxide of tin. 16 


TOPAZ.— Don ault-Wiel and. 


White strass. 1000 

Clear yellowish orange red glass of antimony. 40 

Purple of cassias. 1 

IMITATION OF TOPAZ. 

White strass. 1000 

Oxide of iron. 10 

EMERALD. 

White colorless strass. 1000 

Pure oxide of copper.'. g 

Oxide of chromium... 0.2 


By addition of oxide of cobalt, the green obtained pre¬ 
sents blue reflections. By increasing the chromium or oxide 
of copper, and adding oxide of iron the green shade may be 
varied and intensified. 






























































glassmakers’ hand-book. 


145 


AMETHYST. 


Colorless strass.1000 

Oxide of manganese. 8 

Oxide of cobalt. 5 

Purple of cassius. 0.2 

AQUA MARINE. 

Colorless strass. 1000 

Glass of antimony. 7 

Oxide of cobalt. 0.4 

SYRIAN GARNET— (Dark Ruby.) 

Colorles strass. 1000 

Glass of antimony. 500 

Purple of cassius. 4 

Oxide of manganese. 4 


Iii the manufacture of artificial stones, the greatest care 
in all the details must be constantly exercised, and many 
points must be observed, which can only be acquired by ex¬ 
perience. The materials must be pure; and pulverized with 
the greatest care before being placed in the crucible. The 
later must be clean and fairly glazed. Repeated sifting of 
the materials is advised, to obtain thorough mixing, but a 
different sieve must be used for different colors, no matter 
how well it may have been cleaned after use. The heat 
must be well graduated, and after melting and fining, cool 
off very slowly, so as to anneal the contents. 

AVENTURIN, VENETIAN— Fremy-Cilemandot. 


Pulverized lead flint. 300 parts. 

Copper scales. 40 “ 

Iron scales. 80 “ 


Cool slowly after melting. This glass will, if properly 
managed, have the peculiar metallic luster, and octahedral 
crystals of Venetian aventurin. 

Enamels are simply easily fusible glasses, colored b} T the 
same metallic oxides as the colored glasses. Lead is usually 
used, except where its influence its deleterious to the colors, 
as in light and fine lined white opaque, where it casts a 
blue tinge on the thin edges of designs. 
















146 


GLASSM AKERS’ HAND-BOOK. 


FUSING POINT, SPECIFIC GRAVITY AND CHEM¬ 
ICAL SYMBOL OF METALS USED 
IN GLASSMAKING. 


NAME. 

Symbol. 

Specific 

Gravity. 

Fusing 

Point. 

Degrees 

Fahr. 

Alumina*. 

. A1 

2.67 

1292 

Antimony. 

. Sb 

6.72 

1150 

Bismuth. 

. Bi 

9.82 

5.07 

Arsenic. 

. As 

7.727 

3,56 

Cobalt*. 

. Co 

8.95 

flron. 

Copper*. 

. Cu 

8.94 

1996 

Gold*. 

. Au 

19.86 

2016 

Iron*. 

. Fe 

7.84 

3500 

Lead. 

. Pb 

11.36 

617 

Manganese. 

. Mn 

13.59 

flron. 

Nickel*. 

. Ni 

8.67 

flron 

Silver. 

. Ag 

10.53 

1873 

Tin. 

. Sn 

7.29 

442 

Zinc*. 

. Zn 

7.14 

7.73 

Lime. 

. Ca 

1.57 


Potash... 


0.875 


Nitre. 

. IvNOS 




CHEMICAL NAMES OF ARTICLES USED IN 

GLASSMAKING. 


Chemical Names. 

Nitric acid. 

Nitro-muriatic acid. 

Sulphate of copper. 

Bitrate Potassium. 

Carbonate calcium. 

Carbonate of potassa. • 

Chloride of sodium. 

Sulphate of iron. 

Smalt. 

Sulphate of potassium. 

Sulphide of lead. 

Sulphate of sodium. 

Silica, silex, rock crystal. 

Oxide of tin. 

Sulphate of arsenic. 

Oxide of calcium. 

Nitrate of silver. 

Chloride of calcium. 

Nitrate of potash (a reducing agent). 
Nitrate of soda (oxydizing agent). 
Sulphuric acid. 

Oxide of potassium. 

Potash, refined. 

Sulphide of arsenic. 

Oxide of, litharge of minium. 

Oxide of iron. 

Hydrate Calcium. 

Oxide of sodium. 

Sulphate of lime. 

Phosphate of lime. 

Sulphate of zinc. 


Common Names. 
Aqua Fortis. 

Aqua regia. 

Blue vitriol. 

Cream of tartar. 

Chalk. 

Salt of tartar. 

Common salt. 

Copperas, or green vitriol. 
Glass colored blue, with cobalt 
Dry alum. 

Galena. 

Glauber salt, or salt cake. 

Pure glass sand. 

Jewelers’ putty. 

King’s yellow. 

Lime. 

Lunar caustic. 

Muriate of lime. 

Niter or saltpeter. 

Niter or satpeter. 

Oil of vitriol. 

Potash. 

Pearl ash. 

Realgar. 

Red lead. 

Rust of iron (crocus martis). 
Slacked lime. 

Soda. 

Plaster Paris. 

Bone ash. 

White vitriol. 


*Refers to wrought metal. fLess than. JEqual to, 

























GLASSMAKERS’ HAND-BOOK. 


147 


MEMOS FOR METAL WORKERS. 


Feldspar contains from 12 to l(i per cent, of potash. 

Human bone contains 86.4 per cent, of phosphate of lime. 
Cattle bones, 90.7 per cent. 

One hundred pounds of lime absorbs 45 pounds of water 
while slacking, and weighs, after such absorption of water, 
131 4-10 pounds. 

Nitrate of soda is a reducing agent, and is used in the 
production of copper ruby, being comparatively free from 
objectionable qualities. If used to excess, however, an 
aventurin glass is the result. 


Borax softens glass, and from its powerful fluxing quality, 
is a most valuable addition to such batches whose constitu¬ 
ents have a tendency toward blistering. Borax makes glass 
very fluid and thin, and thus facilitates the rise of air bub¬ 
bles, and their evaporation and escape. To plate glass- 
makers, this matter is of especial interest. 


Be cautious and considerate, but don’t be too conserva¬ 
tive. “Try all things,” hold fast to that which, upon fair 
trial, is ascertained to be good. Take not too much stock in 
old formulas; hold not fast to an old thing, with the idea that 
there cannot be a better one ; neither reject a thing because 
it is new. “Try all things” for yourself. The old fellows 
were sometimes mistaken. The young chaps, often, are. 


In glazing pots intended for the production of colors, it is 
always advisable to use a more refractory glass than that 
which is to be melted in the pot. For such purpose, a glass 


melted at a high heat, containing a fair amount of alumina, 
and highly silicious, will be found best for the purpose. The 
object being, of course, to prevent the deposit of clay from 
the sides of the pots. 



148 


(i LASSM A K ERS’ H AND-BOOK. 


Nickel, zinc and its carbonates, added in small quantities, 
brighten all greens. 

Soapstone (talc) kaolin and oxide of tin produce a fine, 
bright opaque white. 

For amberina, add 12 per cent, of pulverized slate to a 
gold ruby batch which contains a large amount of lead. 

A glassmaker or glass worker ought to read, and try to 
learn all about his art or trade that any or all in all the past, 
have known. Books are the repositories of knowledge. Go 
to them. Despise no source. Art and knowledge are cos¬ 
mopolitan. If France, Germany, England, Italy, Bohemia 
or Hungary can teach you anything, catch on. Profit by it; 
exploit it. Remember that we are only of to-day ; mankind 
is the vehicle of all knowledge since the dawn of time. 

The easiest and most certain method of procuring the sub¬ 
oxide of copper is to boil a solution of equal parts of sugar 
and sulphate, or rather, acetate of copper in four parts of 
sugar. The sugar takes possession of a portion of the oxy¬ 
gen of the cuprous oxide and reduces it to the suboxide, 
when it may be precipitated in the form of a granular pow¬ 
der of a brilliant red. After about two hours of moderate 
ebullition, the liquid is set aside a little to settle, precipitate 
decanted off, is washed and dried.* 

Kaolin, or, as it is sometimes called, China clay, is often 
purposely added to opal batch, and makes up largely the 
amount of alumina shown to be present in the analysis of 
opal glass, varying from 7 to 20 per cent. It is a fine vari¬ 
ety of clay, resulting from the decomposition of feldspar, and 
is a hydrated silicate of aluminum. It is found in China, 
Japan, Saxony, Cornwall, Limoges, and has been discovered 
in immense quantities in various parts of the United States. 
In connection with cryolite or fluorspar, it makes a fine 
opal, and its cheapness should bring it into general use. 


*Muspratt, Vol. I, Enamels. 



GrLASSM AKERS* HAND-BOOK. 


149 


Among the rules laid down by the French chemists, Lauth 
and Dutailly, wdio analyzed and conducted a long series of 
laboratory experiments for the purpose of ascertaining the 
composition of the old Chinese red glaze for porcelains, 
were, these : The glaze must not, on any account, contain 
too much alumina. 

Since alumina and alkalies have a tendency to induce 
“crackling" in the glaze, this tendency must be neutralized 
by employing borax. 

The stannic oxide must not be omitted, because it aids in 
the reduction of the copper oxide ; the proportion of the 
latter must always be greater than that of the former. 

The red color appears to form best when there is free ex¬ 
posure to the action of the air. Borax also materially fa¬ 
vors the formation of the red color. 

The reduction takes place during the firing; this is fol¬ 
lowed b} T oxidation, and the development of blue or green 
tints, if air be allowed access at the end of the operation, 
hence at this stage it is important to exclude air.* 

The above rules should prove of value to metal makers 
in the production of copper ruby. The three points of sim¬ 
ilarity in ceramics and glassmaking, as shown by above 
researches, are (1) alumina, wdiicli makes glass refractory 
and difficult to fuse, should be avoided, because the ruby 
co'or is yielded only by the copper when in the state of sub¬ 
oxide, brought down by a reducing agent, from a higher 
state of oxidation. 

(2) The reducing agent must be proportioned to the basic 
amount of the batch and the action of the air must be used 
so as to favor the reduction of the particles of copper held 
in solution. 

(3) The melt must be conducted so as to facilitate the ac¬ 
tion of a reducing flame, and prevent an oxidizing fiame by 
the exclusion of air. 


*Moniteur de la Ceramique de la Verrerie, 1890. 



150 


GLASSMAKERS’ HAND-BOOK. 


BIBLIOLOGY OF GLASS— Current Literature. 


[The number of volume is from the first or beginning of magazines without 

regard to series.] 

Glass, All the Year Bound, 27 v., 201 p. 

“ Chamber’s Edenburgh Journal, 3 v., 231 p. and 41 
v., 841 p. 

“ Every Saturday, 9 v., 254p. 

“ Action of Sunlight on, American Journal of Science, 
94 v., 244-310 p. 

u American, Nile’s Begister, 10 v., 308 p. 

“ Ancient. Art Journal, 24 v., 3 p. Antiquary 4 v., 

75, 152, 199 p. 

“ Art Work in, Dublin University Magazine, 95 v., 72 p. 

“ As a Material for Construction, American Architect, 
7 v., 280 p. 

“ Bending, Blowing and Cutting off, Journal Frank¬ 
lin Inst., 0 v., 92-301 p. 

“ Berkshire Crystal, Hours at Home, 11 v., 524 p. 

u Making of Colored, Every Saturday, 9 v., 120 p. 

“ Crystalline, Nature of, American Journal of Science, 
91 v., 10 p. I 

“ Decomposed, Crystallization and Polarization of, 
Journal Franklin Inst., 72 v., 300 p. 

“ Early Christian, Fine Arts Quarterly, 2 v., 378 p. 

u Early Christian, Kitto’s Journal, 34 v., 253 p. 

“ Flint-Glass Factory, Pennj r Magazine, 10 v., 81 p. 

“ Manufacture of for Decorative Purposes, American 
Architect, 10 v., 19 p. 

“ Harcourt’s Besearches on, Nature, 4 v., 351 p. 

“ Hardened or Tempered, Practical Magazine, 5 v., 
135 p. 



GLASSM AKERS’ HAND-BOOK. 151 

Glass, Hardened or Tempered, Eclectic Engineering Mag¬ 
azine (Van Nostrand’s) 14 v., 511 p. 

“ Historical Account of, Penny Magazine, 3 v., 178 p. 

Historical Account of, Potter’s American Magazine, 
14 v., 33 y. 

“ Manufacture of, American Journal of Science, 16 v., 

112 p. 

“ Manufacture of, Carey’s American Museum, 6 v., 
119 p. 

“ Manufacture of, Hunt’s Magazine, 27 v., 383-749 p. 
and 28 v., 119-379-513 p. 

“ Manufacture of, Journal Franklin Institute, 42 v., 
271 p. 

“ Manufacture of, Art Journal, 18 v., 25-278 p. 

“ Manufacture of, Chamber’s Journal, 52 v., 478 p. 

“ Manufacture of, Sharpe’s London Magazine, 4 v., 
148, 170, 188 p. 

u Manufacture of, by Ancient and Mediaeval, Cornhill 
Magazine, 16 v., 580 p. 

“ and Porcelain Manufacturers by Ancient Egyptians, 
Living Age, 5 v., 527 p. 

“ Curiosities of, Chamber’s Journal, 11 v., 309 p. 

“ Curiosities of, Electic Review, 90 v., 289 p. 

u Manufacture in Bohemia, Journal Franklin Inst., 39 
v., 109, 183, 273 p. 

u Manufacture in India, Journal Franklin Inst., 5 v., 
391 p. 

“ Manufacture of Crown and Sheet, Journal Franklin 
Inst., 62 v., 205, 275 p. 

“ Manufacture of Filigree, Flint and Crown, Journal 
Franklin Inst,, 41 v., 268, 346, 408 and 42 v., 342 p. 

“ Manufacture of Polished Sheet, Journal Franklin 
Inst., 80 v , 126 p. 

“ of Bohemia, International Magazine, 4 v., 291 p. 

“ Optical Constants of, American Journal Science, 115 
v., 269 p. 


152 


GLASSMAKERS’ HAND-BOOK. 

Glass, Origin and History of, Journal Franklin Inst., 5 v., 
103 p. 

“ Painted, in Household Decoration, Harper’s Maga¬ 
zine, 59 y., 655 p. 

“ Plate, Chamber’s Joural, 58 v., 807 p.; Electic Mag¬ 
azine, 22 v., 552 p. 

“ Plate, Machinery for Manufacture of, JournakFrank- 
lin Inst., 78 v;, 397 p. 

“ Prince Rupert’s Drops, Popular Science Magazine, 8 
v., 315 p. 

u Silvering and Gilding of, Journal Franklin Inst., 
62 v., 318 p. 

“ Silvering, Art of, Chamber’s Journal, 15 v., 63 p. 

“ Silvering, Process for, Journal Franklin Inst., 44 v., 
248 p. 

“ Soluble, Journal Franklin Inst., 64 v., 121,194, 265 p. 

“ Soluble, Eclectic Engineering Magazine, (Van Nos¬ 
trand’s), 3 v., 496 p. 

“ Soluble, Production of, Practical Magazine, 7 v., 336 p. 

“ Stained, Potter’s American Magazine, 8 v., 331 p.; 
Art Journal, 11 v., 38 p. 

“ Stained, Art Journal, 33 v., 69 p. ; Chamber’s Jour¬ 
nal, 56 v., 519 p. 

“ Strength of Various Kinds of, Journal Franklin Inst., 
69 v., 311 p. 

“ Toughened, Popular Science Review, 14 v., 225 p. 

“ Toughened, Eclectic Magazine, 85 v., 457 p. 

“ Toughened, Popular Science Magazine, 7 v., 554 p. 

u Toughened, Living Age, 130 v., 185 p. 

“ Toughened, Eclectic Engineering Magazine, (Van 
Nostrand’s), 13 v., 416 p. 

u Toughened, Practical Magazine, 5 v., 294 p. 

“ Toughened, Manufacture of, Journal Franklin Inst., 
102 v., 371 p.; 103 v., 45 p. 

“ Toughened, Manufact ure of, Practical Magazine, 6 v., 
292 p. and 5 v., 341 > p. 


Glass, 

u 

u 


u 

u 


u 


u 

u 


u 


LL 


LL 

LL 


LL 


LL 


LL 


LL 


LL 
L L 


LL 


GLASSMAKERS’ HAND-BOOK. 153 


Venetian, Antiquary, 4 v., 75 p. 

Ancient and Modern, Cornliill Magazine, 19 v., 459 p. 
Venetian and Enamel Mosaics, Every Saturday, 7 v., 

601 p. 

Venetian, Modern, Art Journal, 32 v., 58 p. 
Venetian, Revival of, Art Journal, 32 v., 58 p. 
Blowing, Art of, Journal Franklin Inst., 15 v., 254, 
327 p. 


As a Fine Art, Harper’s Magazine, 42 v., 337 p. 

Globe and Cylinders, Journal Franklin Inst., 69 v., 
63 p. 

Painting, Art Journal, 21 v., 231 p. 

Painting, Journal Franklin Inst., 42 v., 276, 479 p. 
Staining, Journal Fanklin Inst., 41 v., 181 p. 
Threads, Journal Franklin Inst., 28 v., 367 p. 
Regenerating Gas Furnaces for, Practical Magazine, 
6 v., 71 p. 

and Glassmakers, Magazine Western History, 3 v., 


367 p. 

Manufacture of, at Pittsburgh, Magazine Western 
History, 3 v., 367 p. 

Erosion of, Nature, 31 v., 360, 388 p. 

Improvement in Manufacture of, Journal Franklin 
Inst., 118 v., 132 p. 

Carving as an Art, Art Journal, 37 v., 141, 309, 378 p. 
Stained, Modern French, Art Journal, 37 v., 20 p. 
Tempered, Eclectic Engineering, (Van Nostrand’s), 
33 v., 105 p. 


154 


GLASSMAKERS’ HAND-BOOK. 


PRINCIPAL WORKS CONSULTED. 


In the preparation of Glassmakers’ Hand-book we have 
made free use of, and acknowledge our indebtedness to 
Aiken’s Dictionary of Chemistry ; Benrath’s Glasfabrika¬ 
tion; Bontemp’s Guide du Verrier ; Henrivaux’s Le verre 
et le cristall; Peligot’s Le verre, son historie, sa fabrikation ; 
Tcheusclmer’s Handbucli der Glasfabrikation; Colne’s Re¬ 
port, Glass and Glassware, Paris Exposition, 1878 ; Jos. D. 
Weeks’ Report on the Manufacture of Glass, Tenth Census, 
U. S., Box, Treatise on Heat; Gerner, Die Glasfabrikation ; 
Tomlinson’s Cyclopedia; Muspratt’s Chemistry; Watts’ 
Dictionary of Chemistry; Payen’s Industrial Chemistry; 
Lippincott’s Encyclopedia of Chemistry; Knapp’s Tech¬ 
nology ; Glassmaking, Powell, Chance, Harris; Clievreul, on 
Colors ; Journal of the Franklin Institute; Acids, Alkalies 
and Salts, Richardson and Watts, and Crookes’ Select 
Methods of Chemical Analysis. 

We have also made generous-use of articles and informa¬ 
tion appearing in Sprechsaal, Diamant, Dingler’s Polytech- 
niches Journal, Glasliuette, Moniteur de la Ceramique, 
and the Jahres Berichte uber die Leistungen der Chemi- 
sclien Technologic. 

ERRATA AND CORRECTION. 


In the fifth paragraph, on page 13, referring to oxide of 
iron, the proper reading is peroxide, not protoxide, where it 
refers to “ yellow of a sliglijtly brownish tinge.” 

In copper ruby recipes, Nos. 6 and 7, page 90, read sulpli- 
ret of copper, instead of sulphate ; and sulphide of sodium, 
not sulphate. 




13ST ID IE IXI. 


DIVISIONAL. 

Page. 

Amber bottle glass, ..... 59 

Amberina, how made, ..... 148 
Amethyst, recipes for, .... 90-145 

Analysis of glass, Bon temp’s method, . . 113-118 

Analysis of lead flint glass, ... 63 

Annealing glass, .... 109-113 

Architectural glass, ..... 47 

Art glass, . . . . . .92 

Aqua marine, recipe for, .... 145 

Aventurin, analysis of, . . . . 143 

Aventurin, Venetian, recipe for, . . . 154 

Bibliology of glass in curren literature, . . 150-153 

Black glass, . . . . . .91 

Black glass, recipes for, . . . .91,92 

Blue glass, . . . . . .72 

Blue glass, recipes for, . . . 72,73 

Borax, action of . . . . . . 147 

Chemical names of materials used in glassmaking, 146 

Chemical and nommon names of articles used in glass- 

making, . . . . .146 

Colors, complementary, . . . . .94 

Colors, modifications of, ... 94,95 

Colors, modifications, produced by contact of, 96-99 

Colored glass, . . . . .68 

Composition of glass, . . . . 14 

Copper, suboxide of, how made, . . . 146 

Crude materials for glass making, ... 1 

Decolorizing materials, . . . • .7 

Dutailly and Lauth, researches of, . . . 149 

Enamels, ....... 145 




156 


glassmakers ? hand-book. 


BAGE. 


Faults in the glass, . 

Fine English crystal recipes, 

Fining, or standing off, . 

Flint hollow-ware, .... 

French crystal recipes, .... 

Furnaces and pots, .... 

Fusing point of metals used in glassmaking, 

Fusing point, specific gravity and chemical symbols 
metals used in glassmaking, 

Garnet, Syrian, recipe for, 

General 1 lints on coloring, .... 
General rules for making colors, 

German flint recipes, ..... 
Glass gall, (salt water), 

Glazing of pots for color, .... 

Green bottle glass, .... 

Green bottle glass recipes, .... 
Green glass, ..... 
Green glass, recipes for, .... 


32 
. 64 

31 
. 54 

64 
. 35 

146 

of 

146 

145 

11 

69 

64 

. 28 

147 
56 
59 
74 


Kaolin, used in opal, batch. 


148 


Light and color, analysis of, 
Lead crystal, in open pots, 
Lime glass recipes, 


93 

64 

66 


Materials, used in glassmaking, chemical and common 
names for, 

Memos for metal makers, 

Memos for metal workers, 

Metallic oxides, chemical symbols of, 

Metallic oxides, fusing points of, 

Metallic oxides, specific gravity of, . 

Opal and alabaster glass, 

Opal glass, analysis of, . \ . 

Opal, colored basic, recipes for, 

Opal glass, recipes for, 

Optical glass recipes, 

Ordinary green bottle glass, analysis of, 

Other raw materials, 

Ovens and leers, 

Oxides, metallic, vitrification of earjths by, 


146 
147-149 
147-149 

147 


146 

79,80 
82 
84, 85 
82-84 
65 
58 
4 
38 

99-102 


GLASSM AKERS’ HAND-BOOK. 157 

' . Page. 

Plate glass, ...... 49 

Plate glass, analysis of, . . . . 53 

Plate glass recipes, ..... 51 

Potash and sodium, indirect estimation of, . 136-139 

Potash, a new test for, . . . . 118 

Potash, estimation of, .... 118-125 

Potash from soda, separation of, . . . 135,136 

Preface, ...... 

Preparation of the batch, . ... 22 

Recipes for Hint hollow-ware, . . . .55 

Recipes for lead crystal, . . . . 61 

Red glaze for porcelains, rules for, . . . 149 

Red glaze, rules for production of, applicable to copper 

ruby, ...... 149 

Ruby, copper, ..... 88,89 

Ruby, copper, recipes for, .... 89, 90 

Ruby, gold and copper, . . . . 85-87 

Ruby, gold, recipes for, c 87 

Semi-white sheet glass, . . . 45 

Silvering glass, .... 139-142 

Soda ash, analysis of, .... 129-134 

Soda, estimation of, soluble sulphides in, . 134,135 

Sodium, (salt cake) analysis of, . . . 126-129 

Special action of different constituents, . . 8 

Specific gravity of materials used in glassmaking 146 

Strass, and artificial gems, . .. . 142-145 

The melt, ...... 26 

The melt, crystal and flint hollow-ware, . . 29 

Violet glass, recipes for, . . . .73,74 

Vitrification of earths with saline bodies, . 102-104 

Vitrifying materials, action of, on crucibles containing 

them, ...... 104-109 

Window glass, . • • • • 40 

Window glass recipes, . . . • .42 

Yellow glass, . . • • • • 77 

Yellow glass, recipes for, . . . .78 


INDEX 


DETAILED. 

A. 

Acid, hydrofluoric, action of, - 

Action of different constituents, - 

Alkalies, excess of - 

Alkalies, increase fusibility, - 

Alkalies, use of impure, require high temperature, 

Alumina, accidentally and incidentally present, 

Alumina, purposely added to opal batch, 

Alumina, in granite - 

Alumina increases refractoriness of glass, - 
Alumina, presence of, in green bottles, not objectionable, 
Alumina, amount of, present in rocks, 

Alumina, in opal, - 

Amber bottles, recipes for making, - 
American pressed glass, recipes for, - 
Amethyst, recipe for, ... 

Antique glass, - 
Analysis of glass, - 
Analysis of glass, Bontemp’s method, - 
Analysis of potash, - 

Analysis of salt cake, - 
Analysis of soda ash, - 

Analysis of aventurin, - 
Analysis of constituents of batch, necessity of 
Analysis, importance of. - 

Analysts of Glass : 

American pressed glass, 

Ancient glass, - 
Bohemian bottle, A. 

Bohemian plate, - 
By Iienrivaux and Pelouze, 

English window, - 


Page. 

17 
8 

18 
15 
32 

3 
3 
fl 
9 

56 

57 

- 79 
59 

- 67 
90 
48 

113 
113-118 
118-125 
126-129 
129-134 
143 

r- 

/ 

- 23 

67 

20 

14 

14 

50 

- 14 



galssmAkers’ hand-book. 


159 


Page. 

English crystal, ----- 14 

French bottle, - - - - - 14 

French crystal, - - - - 14 

French plate glass, Jaeckel, ... 50 

French window, 14 

German optical, - - - - - 14 

Green bottles, foreign, 58 

Guano, Baker’s and Jarvis’ Island, - - 68 

Guinand’s optical, 14 

Lead flint - - - - - - 20 

Lead flint glass, - - - - 68 

Nineteen foreign glasses, - - - - 68 

Opal, European and American, - - 82 

Of Light and Color, - - - - 98 

Plate, French, - - - - - 14 

Salt water - - - - 28 

Semi-crystal, ----- 63 

White soda glass, - - - - - 20 

White potash glass, 20 

Annealing glass, .... 109-113 

Annealing glass, table showing researches of Schott, 111 

Annealing glass, molecular movement during process 


of, 


111-112 

- 39 
40 

- 10 

8 

- 10 
99, 102, 103 
13, 47, 48 


Annealing oven, improved. 

Annealing ovens, improvements in, suggested, 

Antimoneous acid, how produced, 

Antimony, a decolorizer, 

Antimony, sulphide of, for yellow, 

Archard, researches of, 

Architectural glass, - - - 

Arseneous acid, temperature at which influence is ex¬ 
erted, ------ 8 

Arsenic, use of, - - - - - 7, 45 

Arsenic, used in excess, effect of, - - - 8 

Art tiles, glass, - - - - - 48 

Aid glass, ------ 92 

Aqua-marine, Bohemian, recipe for, - - - 75 

B 

Baccarat, loss of material at, - - - 60 

Baryta, used in European works, - - 3 

Baryta, increased density and higher polish resulting 

from use of, - - - - - 3 


100 (tLASSMAKERS* hand-book. 


Baryta, as a substitute for soda‘ 

Baryta, free from iron, 

Baryta as a substitute for oxide of lead, 

Barff, Prof., ou ruby stain, quoted, 

Basalt, analysis of, - 
Basic proportions of Hint hollow-ware, 

Batch, evaporation and deposits of, 

Batch, preparation of, - 
Batch, how charged, ... 

Bergman’s analysis of lava, - - * - 

Black glass, - 

Black glass, recipes for, - 
Blast, cold, use of in American factories, 

Blisters, - 

Blue, by cobalt, - 

Blue for sheet glass, - 

Blue glass, cobalt, 

Blue glass, zaffer, .... 

Blue glass, - 
Blue glass, recipes for, 

Blue glass for casing, - 

Bod}^ and casing glass, necessity of similarity in com 
position of, - 

Bohemian crystal, composition of, 

Bohemian fluorescent green, recipe for, 

Bohemian hollow-ware, recipes for, 

Boiling over of pots, results of, 

Bologne’s flask, - - - - 

Bone ash, in opal, - 

Bontemps optical glass, recipes for, 

Bontemp’s, glass, method of analysis, 

Borax,addition of to body glass for casing,recommended 
Bottles, amber, recipes for making, 

Bottles, breakage of, in Pasteurizing process, 

Bottles, for export, tests of, 

Bottles, foreign, analysis of, 

Bottles, green, recipes for making, 

Bottom glass in pots, how to distribute, 

Breweries, Western, tests of bottles at, 

Brilliancy increased by lead, 

Brilliant green, from chrome, 

Bubbles, cause of, - 


GLASSMAKERS’ HAND-BOOK. 


161 


Bisque finish, how produced, - 
Bubbles, how to drive off, - 
Burmese ware, how produced, - 

c 

California imported bottles, - 

California in need of glass factories, 

Carbonacious matter, objectionable, 

Carbonic acid, disengagement of, 

Carbon, as a colorizer, - 

Carbon, use of, - 

Carbon, when use of should be avoided, 

Cars, iron, recommended for annealing glass, - 

Casing green, recipe for, - 

Chalk, free from iron, - 

Chalk, European deposits, - 

Chalk, a carbonate of lime, 

Champagne bottles, foreign, analysis of, 

Chance’s optical glass, recipes for, 

Chance, nothing should be left to it, 

Changes in color, cause of, - 
Charcoal, amount used, - 

Charcoal, for yellow, - 

Charcoal to drive off glass gall, - 
Charcoal, use of in salt cake batch, 

Chimneys, lamp, should be made to last, 

Chimneys, lamp, American lead, exported, 

Chrome, feeble color imparted by, - 
Chrome for green, - 

Chrome, sesquioxide, for green, - 
Clay, added to green glass batch, 

Cleanliness in mixing room, importance of, 
Clemandot on nickel plating blow pipes, 

Cobalt as a colorer, - 
Cobalt as a decolorer, - 
Cobalt blue, - 

Cobalt, different effect of, on soda and potash glass, 

Coke, use of, - 

Collier, P., chemical experiments of, 

Colne, Charles, quoted, - 
Color, how to reduce, - 
Color, source of, 

Color tests, how to conduct, - 
Color scale, use of, - 


Page. 
- 81 
31, 32 
81-148 


5 

5 

7 

- 32 
58, 77 

25 
25-26 

- 40 
76 

3 

3 

o 

58 

- • 65 

33 

- 17 

26 

- 10 

9 

25-28 

113 

- 113 

74 

- 10 
13 

- 57 
23 

- 61 
10 

8 

11 



66 

71 

93 


- 71 

48 


162 GLASSMAKERS’ HAND-BOOK. 

Page. 

Colored glass, - - - - - - 68 

Coloring, general hints on, - - - H 

Colors, complementary, - 94, 97, 98 

Colors, for green bottle glass, - - - 56 

.Colors, general rules for making, - - - 99 

Colors, modifications of, - 94-96 

Cooling, rapid, effect on glass, . - - - 16 

Common white hollow-ware, recipes for, - - 55, 56 

Component constituents cannot be substituted for one 

another, - - - 8-9 

Composition of glass, - - - - - 14 

Composition of foreign glass, 14 

Constituents of glass gall. - - - - 28 

Copper, oxide of, for green, - 10 

Copper, protoxide, colors green, - - - 13 

Copper, oxide of, how produced, - 10 

Copper ruby for casing, - 10 

Copper ruby, cased on a lime body glass, - - 70 

Copper ruby recipes, correction of, - - - 154 

Copper, suboxide, for ruby, - 13 

Copper, suboxide of, - 89 

Copper, use of, for “London smoke,’' - - -10 

Crucibles, vitrifying effect of materials on, - - 104-106 

Cryolite, amount used, in opal, - - - 80 

Cryolite, effect on pots, - - - -4,13 

Crystal glass, - - - - - 59 

Crystal glass, recipes for making, - 64 

(Juliet, absence of, increases strength of bottles, - 56 

Cullet, amount used, .... 4 

Cullet, colored, how to be added, - - - 70 

Cullet, effect of use of on glass, - - - 4 

Cullet, how treated, - - - - - 4 

Cullet, how cleansed, - 61 

Cullet, how to prevent accumulation of, - - 27 

Cullet, overcharges of, to be avoided - - 44 

Cullet should be cleaned, - - 4 

Cullet, should be pulverized, ... 25 

Cullet, use of, - - - - - 4, 26 

Cullet, use of to be avoided in the manufacture of high 

pressure bottles, - - - . 4 

Cullet, use should be guarded, - - 4 

Cut glass, American, first prize at Paris Exposition, 60 

Cylinder glass, fluted, how blown, - - 42 

Cylinder glass, fluted, method of flattening, - 42 


GALSSMAKERS’ HAND-BOOK. 


163 


D 

t-w . . Page. 

Decomposition of glass, cause of, - - - 17 

Diamant, referred to, - - - 43 

Dingler’s Polytechnical Journal quoted. - - 53 

Donault-Wieland, services of, - 443 

Donnenberg’s analysis of lava, ... (5 

Drapers analysis of guano, - - - - 68 

Dullness in sheet glass, cause of, - - 17 

Dumas, analysis of Strass, - 443 

Dutailley and Lauth, on use of borax for porcelain. 70 

E 

Elements that discolor glass, - 7 

Emerald green by oxide of copper, - 10 

Emerald, recipe for making, - - - 144 

Emmerling, researches of, - - - - 18 

English crystal, receipts for making, 04 

Errata and correction, - 154 

Estimating potash, - 118-121 

Estimation, indirect, of potash and sodium, - 136 

Estimation of soluble sulphides in soda and soda ash, 134 
Etching, acid, to produce bisque finish, - - 81 

Even textured glass for casing, - 70 

Exceptions to the rule governing the addition of colored 

cullet, - - - - - 70 

Excuses should not be made nor accepted - 35 

Experts, European, compliment American manufactu¬ 
rers of opalescent window glass, - - 48 

Export beer bottles, Pasteurizing of, - 56 

Export beer bottles, breakage of, in Pasteurizing 

process, - - - - - - 56 

Export beer'bottles, tests of, - 56 

Extension of glass industry, South and Westward, - 5 


F 

Faraday on specific gravity of glass, 15 

Faults in glass, - - - - 33, 34 

Faults in glass, cause of 33 

Faults in glass, removal of, - - 34 

Feldspar, for opal, - - - - -79, 80 

Finkener, method of separating potash from sodium, 135 
Fining glass, - - - - - 31 

Flattening plates, iron, - - - - 41 


164 


GLASSM AKERS 7 HAND-BOOIv. 


Page. 


in 


Flattening plates, iron, described by Moritz, 
Sprechsaal, - - - • - 

Flattening plates, iron, nickel plating of, suggested 
Flattening plates, iron, used in Germany, 

Flattening plates, perforated iron, 

Flattening ovens, advantage of small ones, 

Flattening stones, improvements, 

Flint fruit jars, ----- 
Flint hollow-ware, - 

Flint liollow-ware, recipes for, 

Flint hollow-ware, salt cake, recipes for, 

Fluorescent Bohemian green, recipe for, 

Fluorspar, for opal, - - - - 

Fluted cylinder glass, - 

Fluted cylinder glass, how blown - 
Flux, action of, - 

Foreign bottles, analysis of, - 

Foreign glass, constituents of 

Freight, cost of, will extend glass industry South and 
West, ------ 

French blue, recipes for, - 

French crystal, recipes for making, 

French green, recipe for, - 

French violet, recipes for, 

Fritting, usefulness of, - 
Fruit Jars, flint preferred, - 
Furnace construction improved, 

Furnaces, round, advantages of, 

Furnaces regenerative, advantages of - 
Fusibility increased by soda and potash, - 
Fusing point of gold and copper, 

Fusion, aided by metallic oxides, 

Fusion, aided by pulverized materials, 

Fusion, point of, color developed at, 

Fusion rendered difficult by presence of alumina, 

Fuss, demonstrations of, regarding gold ruby, 

Fritting, discontinued, - - 

Gr 

Gaffield, researches of, - 
Gems, artificial, recipes for, 

Gerhard, researches of, .... 
German flint, recipes for making, 


41 
41 
41 
- 41 

38 
■ 41 

54 

• 54 
55, 56 

• 56 


79, 


80 

41 

42 
27 
58 
14 


o 

73 
64-65 
75, 76 

74 


25 

54 

34 

37 

37 

9 

88 

71 

25 

11 

9 

11 

25 


7, 21 
144 
104-106 
64 


glassmAkers’ hand-book. 


165 


Gerner on tint imparted by oxide of zinc, 
Girardin, analysis of glass gall, 

Glass, antique, ..... 
Glass, composition of, 

Glass, crystal, ..... 
Glass, fining of, . . . 

Glass gall, constituents of, 

Glass gall must be removed before color is added, 
Glass, hand blown, tendency to return to, 

Glass, how it should be compounded, 

Glass, how to analyze, .... 
Glass, liability to change color, 

Glass, lime, for body for casing, 

Glass, silvering of, 
x Glass, specific gravity of, 

Glass, structural defects of, 

Glass, structural laminations of, . 

Glauber salt, amount used in window glass, 
Glauber salt, loss of during melt, 

Goduret, director Baccarat works, quoted, . 
Gold, how to dissolve, 

Gold ruby batch, how prepared. 

Gold ruby, cased on lime body glass, 

Grade, uniform high, of American materials, 
Granite, constituents of, 

Granite, St. Gothard, analysis of, - 
Grass green from chrome, 

Green bottles, analysis of, 

Green bottle glass, .... 

Green from iron and copper, 

Green glass, ..... 

Grey glass, how made, .... 
Green hue imparted by uranium, 

Grenish tint, how neutralized, 

Guano, a substitute for cryolite, 

Guano for opal, . . 

‘‘Guess work” should be forbidden, . 

Guinand’s optical glass, recipe for, 

HE 

Hardness of glass increased by lime, 

Heat, influence of, on glass, 


Page. 


• 

52 

27 

• 

48 

14 


OVJ 

31 

oc 


11 

XO 


oy 

24 

113 - 

-118 

rr 

t 

• 

70 

139 


15 

111 - 

-112 

111 - 

-112 

2 

- 

26 

60 

• 

85 

11 

• 

70 

24 

- 

6 

6 

• 

10 


Oo 

56 

• 

10 

74 

• 

13 

12 

• 

7 

68 

• 

11 

25 

. 

65 


9 

16 


166 GLASSMAKERS’ HAND-BOOK. 


Higli pressure bottles, .... 
Hollow ware, common, recipes for, . 

Hollow-ware, flint, .... 

Hollow ware, salt cake, recipes for, 

Homogenity, lack of, .... 

i 

Uglier J s analysis of lava, 

Intensity of color, how to reduce, . 

Iron, added to cobalt, strengthens blue, 

Iron, amount of, present in rocks, . 

Iron a discolorer 

Iron, not objectionable in green bottle manufacture, 
Iron, prevented on blow pipes by nickel plating, 
Iron, how extracted from cullet, 

Iron, strengthens uranium green, 

Iron, green tint from, .... 

Iron nearly always present, 

Iron, presence of in sand, lime, etc., 

Iron, oxide of, amount in bottle glass, . 

Iron, protoxide, fusibility of, 

Iron, protoxide of, for green, 

Iron, protoxide of, (see errata and correction), 

Iron, sesquioxide of. 

Iron, use of, in black glass, . . . . 

J 

Jack brick, perforated, use of, commended, 


Page. 

. 24 

55—56 
54 
56 
33 , 34 


6 

71 

72 
57 

r- 

i 

56 

61 

61 

75 

13 

4 

4 

21 

9 

10 

10 

10 

10 


31 


K 

Kaolin, purposely added to glass batch, 
Kinkled cylinder glass, 

Klaproth, researches of, . . 

Knowledge, technical, importance of, 
Kolin, on use of nickel and antimony, 
Koninck, analysis of potash, 

Koninck, new method of, to test potash, 

L 

Lamp chimneys, annealing of, 

Lava, Bergman’s analysis of, 

Lava, constituents of, 

Lava, Ilgner’s analysis of, 


o/ 

41 

105-106 
22 , 23 
8 

125 
. 118 


113 

6 

6 

6 


GLASSMAKERS’ HAND-BOOK. 


167 


Lava, Myer and Donnenberger’s analysis of, 
Lava used in Europe, 

Lead added to lime glass for coloring, . 

Lead crystal, .... 

Lead crystal, recipes for, 

Lead glass, composition of, . 

Lead, fusibility of, .... 

Lead flint, analysis of, 

Leadless glass, blue, 

Lead glass for blue, .... 
Lead, glass of, during melt, . 

Lead glass, superior brilliancy of, . 

Lead in opal, ..... 
Lead opalescent, recipe for, . 

Lead potash glass best for blue, 

Leer boxes, heavy iron, recommended, 

Leer, modern, an abomination, 

Leer, necessity of improvements in. 

Lenses for lighthouses, .... 
Lens, Lick Observatory, 

Lime, action of, in pot, .... 
Lime, amount of, in opal, 

Lime crystal, recipes for, 

Lime, effect on color, 

Lime, effect on pots, .... 
Lime glass, American, at Paris Exposition, 

Lime glass, as a body for ruby casing, 

Lime glass, composition of, . 

Lime, ground, ..... 
Lime increases hardness, 

Lime, loss of, in melt, . 

Lime, increased amount of, used in modern glass, 
Lime opalescent, recipe for, 

Lime iron in, to be avoided, 

Lime, result of, used in excess, 

Lime, unburned, .... 

Lime, unburned, preferable,. 

Light, refracting power increased by lead, 

Loam purpsoely added to green glass batch, 

“ London smoke produced by copper and iron, 
Luck, the Jack-o’-Lantern, . 

Lustre increased by use of lime, 


Page. 

6 

6 

. 71 

61 

62 , 64-65 
19 
9 
63 
11 
11 
26 
71 
80 
84 

. 72 

113 

. 113 

39 
22 

. 66 
3 

80 

. 62 
3 

. 3 

66 
70 
19 
2 , 45 
9 

. 26 
54 
84 
2 
3 
2 
2 
9 

57 

10 


GLASSM AKERS* HAND-BOOK. 


168 


M 


Page. 


Macbeth, Geo. A., & Co., referred to, 
Machinery for mixing, advantages of, 
Manganese, coloring power of, 

Manganese, effect of excessive use of, 
Manganese, fusibility of, 

Manganese, masking power of, 

Manganese, tint imparted to plate glass, 
Manganese, use of,. 

Manganese, use of discouraged, for lighthouse 
Manganese, use of, abandoned in Europe, . 
Manganese, yellow tint imparted by, 
Marbleized glass, how made, 

Materials, effects of, on crucibles, 

Materials, effect of different, on glass, 
Material, loss of, during the melt, 

Materials, loss of, during the melt, . 

Materials of the batch should be weighed, 


lenses, 


113 

25 
13 

8 
9 
7 
51 
7 

22 
7 

. 17 

85 

104-109 

57 

60 

26 
. 25 


Melt, how conducted, .... 

Melt, how it proceeds, . 

Melt should be graduated, .... 
Metallic oxides, color opal, . 

Metallic oxides, how to be added to batch, . 

Metallic oxides, how to hold in suspension, 

Metallic oxides, power of staining silicates, effected by 


26 

27 

11 

80 

70 

71 


temperature, 

Metallic oxides, specific gravity of, 

Metallic oxides, vitrification of earths by, 
Milkiness caused by excessive use of arsenic, 
Mixing, improper, faults caused by, 

Mohr, Dr. F., estimation of potash, 

Moisture, effect of, on glass, . 

Molds, nickel plated, in France, 

Monkey pots, use of, 

Monkey pots, use of, commended, 

Morveau, researches of, 

Muffle, silver stain, 

Mushet, experiments of, 

Muspratt, on use of salt cake in plate glass 


. 14 

70 

99-101 

8 

25 

125 

17 

61 

30 

. , 71 

102-104 
11-14 
108-109 
manufac¬ 


ture, 

Muspratt, specific gravity of glass, 


49 

15 


glassmAkers’ hand-book. 


169 


NT 

Nickel, color imparted by, 

Nickel combined with cobalt, 

Nickel, effect of, used in excess, 

Nickel, native state, 

Nitrate of potash, reaction of before fusion, 
Nickel/, oxide, color of, 

Nickel, oxide of. in window glass, 

Nickel, permanency of color imparted by, 

Nickel plating of blow-pipes recommended, 
Nickel plating of iron flattening plates suggested, 
Nickel used in manufacture of plate glass, 

Nickel, use of, .... 

Nickel to warm up blues, 

Nitrate of potassa, use of 

Nitre, use of, .... 

o 

Obsidian, analysis of, ... 

Old gold for sheet glass, . 

Opal, . . . . * . 

Opal and alabaster glass, 

Opal, Bastenaire’s recipe for, 

Opal, colored, recipes for, 

Opalescence, .... 

Opalescent, recipes for, 

Opalescent window glass, 

Opal, opacity of, . 

Opal, oxide of tin, .... 

Opal, recipes for, .... 

Opal, ruby tint on, how produced, . 

Optical glass, Bontemps, recipes for, 

Optical glass, Chance, recipes for, 

Optical glass, decomposition of, 

Optical glass, Guinands, recipes for, 

Orange yellow, how produced, . 

Ovens, annealing, .... 

Oxide of tin, for opal, .... 
Oxygen, disengagement of, . 

F 

Particles, strained position of, 

Pasteurizing beer bottles for export, 


Pagb. 

52 

51 

52 
51 

8 

51 
43 

52 
61 
41 
51 

8 , 13 
72 
7 

45 


6 

. 78 

12 , 13 
. 79 

144 
. 85 

80 
. 84 

48 
. 13 

13 
82-84 
81 

. 65 ' 

65 
. 17 

65 

. 10 
38 
. 13 

32 


16 

56 






170 GLASSMAKERS’ HAND-BOOK. 

Page. 

Pomona green, recipes for, . . . .76 

Pattinson on errors of some analysts, . . 130 

Pellatt, Apsley, recipe for English flint, . .72 

Phosphate of lime for opal, . . . . 13 

Phosphate of lime in opal, . . . .81 

Plate glass, ...... 48 

Plate Glass, Analysis of : 

Bohemian, by Peligot, . . . .53 

Charleroi, Belgium, by Benrath, . . 53 

French, by Dumas, Taffaers, Berthier, . . 53 

London and British Plate Glass Co., by Mayer and 

Brazier, ..... 53 

St. Gobain, France, by Jaeckel, . . .53 

Venetian, by Berthier, ... 53 

Plate glass, analysis of, by Jaeckel,. . . .50 

Plate glass, Bastenaire, recipes for, . . 50 

Plate glass, batch for, . . . . .50 

Plate glass, color of, . . . . . 51 

Plate glass, foreign analyses by Berthier, Taffaers, 
Dumas, Peligot, Mayer and Brazier, Jaeckel, Ben- 
rath and Weber, . . . . .53 

Plate glass, oldest batches, .... 49 

Plate glass, oldest, by Henrivaux, . . .49 

Plate glass, oxide of nickel introduced by De Fontenay, 51 
Plate glass, polished, the perfection of the glassmaker’s 

art, ...... 52 

Plate glass, recipe for. by Graeger, . . .49 

Plate glass researches of Faraday, . . 51 

Plate glass, salt cake used in manufacture, . . 49 

Plate glass, soda preferable to potash, . . 51 

Plate glass, St. Gobi an formulas, . . .49 

Plate glass, tint imparted to potash glass by manganese, 51 
Plate glass, tint imparted to soda glass by manganese, 51 
Points to be observed in estimating potash, . 120-121 

Potash, amount of, used abroad, . . < 57 

Potash and sodium, rapid estimation of, . . 138 

Potash, effect on brilliancy, ... 2 

Potash, efficiency of, . . . .2 

Potash, estimation of, . . . . 118 

Potash, estimation of, rules to be observed, . 120-121 

Potash, flint hollow-ware, basic proportions of, . 54 

Potash, how to test, ..... 118 


GLASSMAKERS’ HAND-BOOK 


171 


Potash loss of, during the melt, 

Potash, new test for, 

Potash, separation from sodium, 

Pots boiling over of, . 

Pots, cold, result of, .... 

Pot setting, difficulties of, in old style furnaces, 

Pots, large, difficulty of making fine colors in. 

Pots, “monkey,” use of, .... 

Pots, Neville’s patent,, . 

Pots, “monkey,” for trial tests, 

Pots should be hot when charged, 

Pots, small, used abroad for making colored glass, 
Pots, stoppering of, 

Precht on determination of potash, 

Pressed glass, American, recipes for, 

Pressed pitchers, frailty of same, 

Principles of coloring, .... 

Proper compounding of the batch, 

Proportions, basic, of Hint hollow ware, 

Pulverized glass, advantage of using, 

Pulverizing raw materials, advantage of, 

Pumice stone, analysis of, 

Purity of American lime glass, 

Purple of Cassius, color of, 

Purple of Cassius, composition of, . 

Purple of Cassius, Fuch’s method of preparation, 
Purple of Cassius, German method of preparing, aban 
donexl, ..... 

Purple of Cassius, how made, 

Q 

(Quality of glass, how deteriorated, 

R 

Rapid cooling, effect of, 

Recipe for English flint, Pellatts, 

Recipes for blue glass, 

Recipes for flint hollow-ware, 

Recipes for green glass, . 

Recipes for making green bottles, . 

Recipes for optical glass, 

Recipes to be changed to suit temperatures, 

Record, in test trials, importance of, 


Rage. 

26 

118-125 
. 135 


o 

O' 


37 

30 

30 

62 

71 

26 

23 

30 

121 

67 

112 

93 

8 

54 

71 

25 

6 

67 

11 

86 

11 

11 

86 


27 

16 
72 
, 73 
55 
75, 76 
59 
65 
23 
71 


7: 


17 2 


GLASSMAKERS* HAND-BOOK. 

Page. 

Reducing agents in copper ruby, necessity of, . 69, 88 

Resistance, increased, of modern hollow-ware, . 54 

Resistance of glass, increased by alumina, . 57 

Resistance to atmospheric influences, . . 17,18 

Richardson, analysis of glass gall, ... 28 

Rich cuttings, American, recognized merit of, . . 60 

Rich lead crystal, recipes for, • 62 

Right thing at the right time, importance of doing, 83 

Ronalds, analysis of glass gall, . . .28 

Round furnace, success of, in window glass manufac¬ 
ture, . . . . . . .37 

Ruby batch, Kohns, .... 85 

Ruby batch, Pellatts, . . . . .87 

Ruby batch, Pohls, ..... 87 

Ruby, copper, . . . . . .88 

Ruby, copper, ..... 69 

Ruby from suboxide of copper, . . .13 

Ruby, gold and copper, .... 85 

Ruby, gold and copper batch, how prepared, . . 11 

Ruby, gold and copper, cased on a lime body glass, 70 

Ruby, gold, oxide of tin not necessary for, . .11 

Ruby, gold, recipes for, .... 87 

Ruby, purple of Cassius for, how prepared, . . 11 

Ruby, rapid reduction of furnace temperature favorable 

to development of color of, . . 11 

Ruby, recipes for, .... 89-90 

Ruby tint on opal, how produced, ... 81 

Rule for composition of glass, . . . .19 

Rules for making colors, .... 69 

Rules to be observed in estimating potash, . .120 

8 

Salt cake, amount used in window glass, . . 2 

Salt cake, analysis of, .... 126-128 

Salt cake and glass gall, . . . . 2, 28, 29 

Salt cake bottle glass, recipes for, .' / . 59 

Salt cake hollow-ware, . . . . .56 

Salts, action of solutions of, on glass, . . 18 

Saltpeter, loss of during the melt, . . .26 

Salt water, constiuents of, . * . 28 

Salt water, how neutralized, . . . .25 

Salt water, necessity of removal of, before color is 

added, ...... 56 



GLASSMAKERS* HAND-BOOK. 173 

Page. 

Sand, purity of American, . . . .24 

Sand, where found, . . . . . l, 2 

Satin finish, how produced, . . . .81 

Sawdust, use oi, 26 

Seeds, how to drive off, . . . .31 

Semi-crystal, analysis of, ... 63 

Shades, lead opal, . . . . .84 

Sheet glass, blue, recipe for, ... 73 

Sheet glass, dullness, cause of, . . . 17 

Sheet glass, greenish yellow, recipe for, . . 76 

Sheet glass, ribbed, . . . . .41 

Sheet glass, old gold, recipe for, . . . 78 

Sheet glass, semi-white, recipes for, . . 45-47 

Sheet glass, violet, recipe for, ... 73 

Siemens, granite in bottle manufacture, . . 6 

Silica, in rocks, ...... 1 

Silica, separation of films under atmospheric influences, 17 

Silver, chloride of, for Burmese ware, . . 81 

Silver, oxide of, does not stain silicates at high tem¬ 
peratures, . . . . . .14 

Silver, oxide of, for yellow, . . . . 10 

Silver stain, yellow, . . . . 11, 13 

Slacks, how obviated, .... 35 

Slag used in bottle manufacture, . . 57 

Slag, varying proportions of, ... 7 

Smalt, use of, . . . . . 51 

Smith, J. Denham, method of estimating potash, . 118-21 

Soda ash, analysis of, . . . 129-134 

Soda ash, Jean’s method of analysis, . . 133 

Soda ash manufactured, . . . .2 

Soda, effect on color, .... 2 

Soda, flint liollow-ware, basic proportions of, . . 54 

Soda glass, composition of, . . . . 19 

Soda, loss of, during the melt, . . . .26 

Soluble calcium salts, action of, on glass, . . 18 

Specific gravity of glass, . . . .15 

Specific gravity of metallic oxides, . . . 70 

Standing off, . . . . • .31 

St. Gobain Works, method of silvering glass at, . 140 

Stoppering of pots, . . . . .30 

Strass, analysis of, . . • • 20 

Strass and artificial gems, .... 142 



174 


GLASSMAKERS’ HAND-BOOK. 


Page. 

Strass, base for colored, .... 144 

Strasser, Joseph, discoverer of Strass, . . . 142 

Strass, Donault-Wieland’s analysis of, . . 143 

Strass, Loysel’s recipes for, .... 144 

Strass, recipes for making, .... 144 

Stride in glass, . . . . . .33 

Substitutes for sand, .... 5 

Sulphate in soda, presence of, . . . .28 

Sulphate of antimony, . . . . 10 

Sulphate of soda, amount used in window glass, . 2 

Sulphuric acid, action of on glass, ... 18 

Sunlight, effect on glass, . . 7, 17, 21, 22 


T 

Tanks, compartments of, ... 

Tanks, distinctive advantages of, 

Tanks, economy of, ... 

Tanks, Europeans, leaders in, 

Tanks, gradual adoption of, 

Tanks, technical knowledge required to operate, 
Tate, W., analysis of salt cake, 

Tatlock, K., analysis of potash, 

Teshemacher, method of estimating potash, 
Tests, color, how to conduct, 

Tests of bottles for export, . 

Tiles, art, glass, ..... 
Tin, oxide of, not necessary for gold ruby, . 
Topaz, recipe for making, 

Transparent glass, oldest discovered piece of, 

TJ 

Uranium, fluorescence imparted by, 

Uranium for Burmese ware, 

Uranium, for yellow, .... 
Uranium, for yellow glass, 


. 37 

37 
. 3b 
35, 36 
3b 
36 
. 129 
122,123 
118-121 
. 71 

5b 
. 48 

11 

. 144 

142 


75 

81 

10 

77 


v 

Venetian plate glass, analysis of, 

Violet glass, 

Violet, recipes for, 

Vitrilication of earths by metallic oxides, 


. 53 

13 
73, 74 
99-101 


175 

Page. 


GLASSMAKERS’ HAJfD-BOOK. 


W 


Water, boiling, effect on glass. 

Waviness in glass, cause of, 

Weber’s researches on permanency of* color in plate 
glass, . 

Weyer, improved annealing oven, . 

White flint hollow-ware, recipes for, 

W indow Glass : .... 

Brilliancy of, when flattened on planed iron plates, 
Defects of, . . ' . 

Opalescent, Americans lead in manufacture of, 
Recipes for, ..... 
Recipes for Belgian, .... 

Recipes for Bohemian, . 

Recipes for French, .... 

Recipes for German, . . . . 

Salt cake, recipes for, .... 

Semi-white, recipes for, 


18 

33 


53 

39 
55, 56 

40 

41 
40 
48 

42,43 
44 
44 
44 
44 
43 
45-47 


Y 

Yellow, colorizers for, 

Yellow, delicate tinge of, 

Yellow, from antimony, 

Yellow, from charcoal, 

Yellow, from silver, . 

Yellow glass, colorizers for, 

Yellow glass, from uranium, 

Yellow glass, recipes for, 

A^ellow, orange, how produced, 

Yellow stain, from silver, 

Yellow tinge in lead crystal, 

Yellow tinge, masked by oxide of nickel, 
Y ellow tint from iron, 


11 

. 11 
10 

. 10 
10 
77 

10-11 
. 78 

10 

. 11 

62 

9 

13 


z 

Zaffer, as a decolorer, . . . . .8 

Zaffer, use of, in blue glass, .... 10 

Zinc, use of, . . . . .9 

Zinc, used in manufacture of plate glass at St. Gobain, 52 
Zinc, tint imparted by, . . . . .52 

Zinc, use of, American experience with, . . 52 

Zuckschwerdt, Dr., on analysis of potash, . . 123 


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